Potential of shear-clinching technology for joining of three sheets - Wiesenmayer, Sebastian; Merklein, Marion (Journal of Advanced Joining Processes, 2021)
The load-specific design of car bodies often requires the joining of more than two sheets. However, due to the additional interfaces and the mutual influence of the joining partners, joining of multi-layer sheets is challenging. This applies for welding technologies and in particular for joining by forming processes, which are often limited by the mechanical properties of the joining partners or require additional fasteners. The shear-clinching technology combines shear-cutting and clinching and therefore allows the joining by forming of high-strength materials without additional fasteners or pre-holing. Yet, the process has only been analyzed for two sheets. Thus, the potential of the technology for joining three sheets is investigated within the scope of this work. Starting from a two-sheet joint with punch-sided AA5182-O and die-sided DP600, the upper and the lower sheet are subsequently replaced by two sheets with half the thickness. The shear-clinching process, the joint formation and the resulting load-bearing capacity are analyzed for the joining of three sheets and compared to the two-sheet reference. Shear-clinching of three sheets with DP600 in the middle and the bottom layer was successfully conducted. Under shear load, the load-bearing capacity is comparable to the two-sheet specimens. However, applying tensile load leads to a two-staged failure of the joint and therefore to lower testing forces. When the force is applied to the top and the bottom layer, the joint strength is distinctly reduced, independent from the load direction.<br
Keywords: Joining; Forming; High-strength steel; Aluminum

Potenziale und Grenzen der Simulation in der Fertigungstechnik - Merklein, Marion; Andreas, Kolja; Gröbel, Daniel; Hildenbrand, Philipp; Müller, Martin; Noneder, Johannes; Zimmermann, Andrea; Schneider, Thomas; Vierzigmann, Ulrich (Tagungsband 15. RoundTable - Simulating Manufacturing, 2014)
LFT Import::2019-08-05 (2021)

Praxisnahe Versagensbeschreibung in der Blechumformung - Vergleich zwischen dem mikromechanischen Schädigungsmodell nach Gurson-Tveergard-Needleman und dem Grenzformänderungsschaubild - Gröbel, Daniel; Rösel, Sebastian; Merklein, Marion; Butz, A. (Umformen, Schneiden, Verbinden im Leichtbau - Machbarkeit - Produktivität - Qualität - Tagungsband T36 des 33. EFB-Kolloquiums Blechverarbeitung am 16. und 17. April 2013 in Fellbach, 2013)
LFT Import::2019-08-05 (1889)

Precipitation behaviour and mechanical properties during short‑term heat treatment for tailor heat treated profiles (THTP) of aluminium alloy 6060 T4 - Fröck, Hannes; Graser, Matthias; Milkereit, Benjamin; Reich, Michael; Lechner, Michael; Merklein, Marion; Kessler, Olaf (Materials Science Forum, 2017)
Precipitation hardening aluminium alloys are widely used for automotive applications. To enhance the application of aluminium profiles, improved formability is needed. Tailor Heat Treated Profiles (THTP) with locally different material properties attempt to increase formability e.g. in bending processes. Tailoring of local properties is obtained by a local short-term heat treatment, dissolving the initial precipitate state (retrogression) and still allowing subsequent ageing. In the present study, the dissolution and precipitation behaviour of the aluminium alloy EN AW-6060 T4 was investigated during heating with differential scanning calorimetry (DSC). Heating curves from 20 to 600 °C with heating rates of 0.01 up to 5 K/s were recorded. Interrupted heat treatments with different maximum temperatures were performed in a deformation dilatometer. Immediately afterwards, tensile tests were carried out at room temperature. The course of the recorded mechanical properties as a function of the maximum temperature is discussed with regard to the dissolution and precipitation behaviour during heating. Finally, the aging behaviour of the investigated alloy was recorded after different typical short-term heat treatments and is discussed with reference to the DSC‑curves. The correlation of the microstructure and the mechanical properties enables the derivation of optimal parameters for the development of THTP through a local softening.
CRIS-Team Scopus Importer:2023-03-29
Keywords: Differential scanning calorimetry; Dissolution; EN AW-6060; Precipitation; Re-aging; Tailor heat treated profiles (THTP)

Precise Material Properties as a Prerequisite for FE-Analysis of the Hydroforming of Tailored Welded Blanks - Tolazzi, Massimo; Merklein, Marion (Steel Research International, 2005)
Tailored welded blanks are already used in the series production of deep drawn parts, and are now considered also for other forming technologies, like for example hydroforming. As new materials come into the market, also their combinations in the production of new tailored welded blanks increase, improving on the one hand the possibilities of matching material and functional requirements, but making the material characterisation more difficult on the other hand. For this reason new methods for a fast, precise and flexible characterisation of the mechanical and tribological properties of tailored welded blanks are needed. In particular the FE‐analysis, a powerful instrument for the definition and optimisation of forming processes, needs precise and reproducible material data in order to deliver accurate results. Therefore, when working with tailored welded blanks, it is crucial that the weld line is modelled using mechanical and tribological properties which refer to its structure and surface. This work summarises the methods used for the characterisation of the mechanical properties of the weld line at the chair of manufacturing technology in Erlangen and presents the results obtained for four different steel grades (FeP04, ZStE340, DP450 and TRIP800) and the tailored welded blanks obtained by their combinations. The accuracy of the results obtained in tensile and in friction tests were verified in simple experiments by comparing results from the tests with results from the finite element analysis. These were seen to be in very good accordance, confirming the accuracy of methods used in the material characterisation.
LFT Import::2019-07-16 (1175)
Keywords: Finite element analysis; Friction coefficients; Tailored welded blanks; Tensile test

Prediction of Damage in Small Curvature Bending Processes of High Strength Steels Using Continuum Damage Mechanics Model in 3D Simulation - Tsoupis, Ioannis; Hildering, Sven; Merklein, Marion (Production Engineering, 2013)
Sheet metal bending of modern lightweight materials like high-strength low-alloyed steels (HSLA) is one major challenge in metal forming, because conventional methods of predicting failure in numerical simulation, like the forming limit diagram (FLD), can generally not be applied to bending processes. Furthermore, the damage and failure behaviour of HSLA steels are changing as the fracture mechanisms are mainly depending on the microstructure, which is very fine-grained in HSLA steels composed with different alloying elements compared to established mild steels. Especially for high gradients of strain and stress over the sheet thickness, as they occur in small curvature bending processes, other damage models than the FLD have to be utilised. Within this paper a finite element (FE) 3D model of small curvature bending processes is created. The model includes continuum damage mechanics model in order to predict and study occurring failure by means of ductile coherence loss of the material and crack formation with respect to influencing process parameters. Damage parameters are determined by inverse numerical identification method. The FE-model is strain based validated considering the deformation field at the outer bending edge of the specimen by using an optical strain measurement system. The Lemaitre based damage model is calibrated against the experimental results within metallographic analysis adapting the identified damage parameters to the bending process und thus adjusting the crack occurrence in experiment and simulation. Using this model the bendability of common HSLA steel, used for structural components, is evaluated with respect to occurring damage and failure by numerical analysis. © 2012 German Academic Society for Production Engineering (WGP).
LFT Import::2019-07-29 (1854)
Keywords: Bending; Continuum damage law; High strength steel; Numerical simulation

Presshärten von Tailor Welded Blanks: Werkstoffauswahl, Eigenschaften und Verbindungstechnik - Deinzer, Günter; Stich, A.; Lamprecht, Klaus; Schmid, G.; Rauscher, M.; Merklein, Marion; Lechler, Jürgen (3. Erlanger Workshop Warmblechumformung, 2008)
LFT Import::2019-07-29 (1546)

Pressschweißen von Aluminium-Stahl-Mischverbindungen - Schmid, D.; Neudel, Christian; Zäh, Michael; Merklein, Marion (Lightweight Design, 2012)
LFT Import::2019-07-29 (1824)

Prestressing of cold forging tools for parts with functional elements - Killmann, Martin; Merklein, Marion (XL. Colloquium on Metal Forming, 2022)
An increasing demand for complex part geometries poses challenges to the fatigue strength of cold forging tools. When producing functional elements like gears or carriers, local stress peaks occur in the forging dies. To avoid fatigue failure, an analysis of the stress state and adequate prestressing strategies for non-circular symmetrical cold forging tools are necessary. Therefore, a model process for the closed-die forging of four functional elements is introduced and the resulting stress state analysed numerically. While high compressive stresses and radial displacements are present between the functional elements, there is a tensile stress area with tangential stresses critical for fatigue failure at the head of the functional elements. To counteract this, a local prestressing of functional elements by stress pins is proposed. The pins are pressed into the tool, locally creating radial compressive and tangential tensile stresses. They are well suited for geometries with functional elements, because there are no undesired interactions between pin and process tensile stresses. Even the stress state in tools for more complex part geometries with a higher number of functional elements can be improved that way. However, the height of the local prestressing is still limited by tensile stresses around the pin. <
Keywords: Cold forging; tooling; prestressing; stress pins

Principles for the Heart Treatment Layout of Ultrafine-Grain Aluminium Blanks with Locally Adapted Mechanical Properties - Merklein, Marion; Vogt, Uwe (Proceedings of the COMA 2010, 2009)
EAM Import::2019-03-08

Process-adapted temperature application within a two-stage rivet forming process for high nitrogen steel - Kuball, Clara-Maria; Uhe, Benedikt; Meschut, Gerson; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers Part L-Journal of Materials-Design and Applications, 2022)

Process analysis for deep drawing of tailored heat treated blanks - Kerausch, Michael; Merklein, Marion (Proceedings of the 8th International Conference on Technology of Plasticity (ICTP), 09.-13.10., Verona, Italy, 2005)
This paper will summarize the results of a development to improve the forming performance of hardenable aluminum alloys in deep drawing processes. Experimental investigations show the feasibility to change the mechanical properties with a laser heat treatment by influencing the precipitation structure. This enables to manufacture so called Tailored Heat Treated Blanks (THTB) by a local heat treatment. Introducing mechanical property gradients improves the drawing capabilities of THTB significantly relative to homogenous blanks in the naturally aged condition T4. In case that the deformation zone is softened, the maximum drawing force is reduced, while the force transferring area is not affected by the selective heat treatment. Accordingly the total process energy for drawing THTB is lower in comparison to the conventional deep drawing process. As a result the probability of bottom fracture is reduced and a higher drawing ratio can be attained.
LFT Import::2019-08-05 (1220)

Process and Damage Behaviour of High Strength Steels in Shearing Operations - Hildering, Sven; Tsoupis, Ioannis; Merklein, Marion (Tagungsband XXXII. Verformungskundliches Kolloquium, 2013)
LFT Import::2019-08-05 (1879)

Process Combination for the Manufacturing of Toothed, Thin-Walled Functional Elements by Using Process Adapted Semi-finished Products - Vogel, Manfred; Schulte, Robert Karl; Lechner, Michael; Merklein, Marion (Springer International Publishing, 2021)
The scientific objective is the analysis of a process combination for the manufacturing of toothed, thin-walled functional elements from process-optimized semi-finished products. By using an upsetting, orbital forming as well as a modified flexible rolling process, tailored blanks with flow-optimized properties are manufactured. In this context, a defined material flow control plays a decisive role for the forming of different geometries. In order to pursue a holistic approach, the process limits as well as the potential of the individual processes are identified. With the application of such blanks, geometrically complex components with functional elements such as gears or carriers are formed in a new combined deep-drawing and upsetting process. The aim is to reduce the number of steps in the process chain and thus save energy and resources. Thereby, different levels of functional integration are taken into account with regard to the geometry and arrangement of the functional elements, but also combinations of both.

Process design for the forming of semi-tubular self-piercing rivets made of high nitrogen steel. - Kuball, Clara-Maria; Uhe, Benedikt; Meschut, Gerson; Merklein, Marion (Procedia Manufacturing, 2020)
The aim to reduce pollutant emission has led to a trend towards lightweight construction in car body development during the last years. As a consequence of the resulting need for multi-material design, mechanical joining technologies become increasingly important. Mechanical joining allows for the combination of dissimilar materials, while thermic joining techniques reach their limits. Self-piercing riveting enables the joining of dissimilar materials by using semi-tubular rivets as mechanical fasteners. The rivet production, however, is costly and time-consuming, as the rivets generally have to be hardened, tempered and coated after forming, in order to achieve an adequate strength and corrosion resistance. A promising approach to improve the efficiency of the rivet manufacturing is the use of high-strength high nitrogen steel as rivet material because these additional process steps would not be necessary anymore. As a result of the comparatively high nitrogen content, such steels have various beneficial properties like higher strength, good ductility and improved corrosion resistance. By cold bulk forming of high nitrogen steels high-strength parts can be manufactured due to the strengthening which is caused by the high strain hardening. However, high tool loads thereby have to be expected and are a major challenge during the production process. Consequently, there is a need for appropriate forming strategies. This paper presents key aspects concerning the process design for the manufacturing of semi-tubular self-piercing rivets made of high-strength steel. The aim is to produce the rivets in several forming stages without intermediate heat treatment between the single stages. Due to the high strain hardening of the material, a two stage forming concept will be investigated. Cup-backward extrusion is chosen as the first process step in order to form the rivet shank without forming the rivet foot. Thus, the strain hardening effects in the area of the rivet foot are minimized and the tool loads during the following process step can be reduced. During the second and final forming stage the detailed geometry of the rivet foot and the rivet head is formed. In this context, the effect of different variations, for example concerning the final geometry of the rivet foot, on the tool load is investigated using multistage numerical analysis. Furthermore, the influence of the process temperature on occurring stresses is analysed. Based on the results of the investigations, an adequate forming strategy and a tool concept for the manufacturing of semi-tubular self-piercing rivets made of high-strength steel are presente
Keywords: high nitrogen steel; self-piercing riveting; joining by forming; bulk forming; tool design

Process Design of Aluminum Tailor Heat Treated Blanks - Kahrimanidis, Alexander; Lechner, Michael; Degner, Julia; Wortberg, Daniel; Merklein, Marion (Materials, 2015)
LFT Import::2019-07-29 (2141)
Keywords: Lightweight design; Material model; Tailor heat treated blanks

Processing of 316L hybrid parts consisting of sheet metal and additively manufactured element by Powder Bed Fusion using a laser beam - Papke, Thomas; Merklein, Marion (Procedia CIRP, 2020)
The approach of 316L hybrid parts consisting of sheet metal with additively manufactured element is investigated regarding relative density, warpage and bonding strength between additively manufactured element and sheet metal. Process parameters for manufacturing hybrid parts with relative density of 99.9 % are identified. Warpage is a critical aspect for hybrid parts, which increases with increasing volume energy density. Regarding a proper part design, knowledge of dependencies of bonding strength is essential. The bonding strength is influenced by relative density of the additively manufactured element and remains on one level for increasing volume energy density.
CRIS-Team Scopus Importer:2020-10-30
Keywords: Additive Manufacturing; Hybrid Part; Part Characterization; PBF-LB/M; Sheet Metal; Stainless Steel

Processing of Aluminium Foam Sandwich Tailored Blanks - Dörfler, Stephan Manuel; Otto, Andreas; Merklein, Marion; Geiger, Manfred (Proceedings of the Advanced Metallic Materials, 2003)
LFT Import::2019-08-05 (966)

Process Mechanics in Friction Stir Welding of Magnesium Alloys: Experimental and Numerical Analysis - Buffa, Gianluca; Fratini, Liven; Gnibl, Tobias; Wieland, Michael; Merklein, Marion (Key Engineering Materials, 2012)
Light weight construction is a major task within automotive and aircraft industry due to lower fuel consumption or increase the possible payload. Structural or exterior shell components are more and more manufactured out of aluminum alloys for this reason. A further weight reduction could be achieved by the substitution of aluminum alloys by magnesium alloys. Also the application of blanks with a varying thickness is a possibility to realize light weight design. To combine the advantages of weight reduction by the use of magnesium alloys and tailored welded blanks (TWBs), an effective joining technique is required. Friction Stir Welding can be used for difficult to be welded magnesium alloys to manufacture magnesium TWBs. During this process the different thickness of the two sheets can cause an unequal heat distribution below the tool, affecting material flow and therefore components strength. In the paper the main results of a numerical and experimental campaign on Friction Stir Welding of AZ31 magnesium alloy tailored blanks are presented. The numerical simulation was validated by experimental observations and the occurring bonding conditions have been analyzed in both approaches.© (2012) Trans Tech Publications.
LFT Import::2019-07-29 (1778)
Keywords: Friction stir welding; Material flow; Numerical simulation; Tailored welded blanks

Process Modeling In Cold Forging Considering The Process-Tool-Machine Interactions - Kroiss, Thomas; Engel, Ulf; Merklein, Marion (Proc. of the 10th Int. Conf. on Numerical Methods in Industrial Forming Processes; AIP Conference Proceedings 1252, 2010)
In this paper, a methodic approach is presented for the determination and modeling of the axial deflection characteristic for the whole system of stroke-controlled press and tooling system. This is realized by a combination of experiment and FE simulation. The press characteristic is uniquely measured in experiment. The tooling system characteristic is determined in FE simulation to avoid experimental investigations on various tooling systems. The stiffnesses of press and tooling system are combined to a substitute stiffness that is integrated into the FE process simulation as a spring element. Non-linear initial effects of the press are modeled with a constant shift factor. The approach was applied to a full forward extrusion process on a press with C-frame. A comparison between experiments and results of the integrated FE simulation model showed a high accuracy of the FE model. The simulation model with integrated deflection characteristic represents the entire process behavior and can be used for the calculation of a mathematical process model based on variant simulations and response surfaces. In a subsequent optimization step, an adjusted process and tool design can be determined, that compensates the influence of the deflections on the workpiece dimensions leading to high workpiece accuracy. Using knowledge on the process behavior, the required number of variant simulations was reduced. © 2010 American Institute of Physics.
LFT Import::2019-08-05 (499)
Keywords: Cold Forging; Press Deflection; Process Modeling; Process-Tool-Machine Interactions

Process-oriented validation of hardening models in a cyclic bending test - Rosenschon, Martin; Merklein, Marion (International Conference on the Technology of Plasticity, ICTP 2017, 17-22 September 2017, Cambridge, United Kingdom, 2017)
None
LFT Import::2019-08-05 (2273)
Keywords: Kinematic hardening; Metal forming; Modelling

Production of gears by cold forging - Zimmermann, Andrea; Engel, Ulf; Merklein, Marion; Neher, R. (Int. Conf. on Gears, VDI-Berichte 2199.2, 2013)
LFT Import::2019-08-05 (1917)

Prognose der mechanischen Bauteileigenschaften bei Presshärtprozessen anhand mikrostruktureller und umformtechnischer Zusammenhänge - Springer, R.; Lechler, Jürgen; Stöhr, Thomas; Karbasian, H.; Schaper, M.; Merklein, Marion; Brosius, A.; Tekkaya, A.E. (Tagungsband 3. Erlanger Workshop Warmblechumformung, 2008)
LFT Import::2019-08-05 (196)

Properties of Tool Steels for Application in Hot Stamping - Niederhofer, Philipp; Eger, Kathrin; Schwingenschlögl, Patrik; Merklein, Marion (Steel Research International, 2019)
Hot stamped high-strength steel components for car bodies become increasingly important due to the need to save weight for multiple reasons such as fuel conservation regulations. Tribological systems in tools for hot stamping depend on process parameters and may include, e.g., mechanical and thermal loads as well as adhesive and abrasive wear. Furthermore, the process cycle time should be as short as possible due to economic reasons. Commonly used hot work tool steels mainly suffer from rather low wear resistance, whereas in terms of process cycle time, a high thermal conductivity is desired. Thus, solutions showing optimized combination of key properties for application in hot stamping such as wear resistance, high thermal conductivity, toughness, and hardening behavior need to be found. In this contribution, novel high thermal conductivity hot work tool steels, especially designed for application in hot stamping, are presented and some key properties are compared, e.g., to those of conventional hot work tool steels like 1.2367, which is commonly used in this application. Furthermore, tribological investigations are performed in laboratory tests according to ASTM G65 and G75 as well as a flat strip-drawing test setup using sheets of 22MnB5 under hot stamping conditions.
CRIS-Team WoS Importer:2019-12-10

Proprietà meccaniche di una tecnologia di giunzione innovativa tipo shear-clinching per strutture leggere automobilistiche in acciaio ad altissima resistenza e leghe di alluminio - Hörhold, Réjane; Müller, Martin; Merklein, Marion; Meschut, Gerson (Rivista Italiana della Saldatura, 2017)
Comfort- And safety-related requirements lead to weight increase of automotive structures. Modern constructions in automotive body in white (BIW) production confront this upward weight spiral with multi-material design. This restricts conventional thermal joining technologies. The basic idea of mechanical joining technologies is a force- And formfitting joint. Clinching technologies create a joint only by plastic deformation. The formability of the joining partners limits this technology, especially when joining ultra-highstrength steels (UHSS) in multi-material design. State of the art to realise this is multistage clinching with pre-hole. Industrial applications in BIW are, e.g. the brackets for mouldings in the upper windscreen frame of Daimler's S-class and the battery holder of Daimler's M-class. Innovative shear-clinching enables joining by forming hot formed UHSS and ductile aluminium in a single-stage process. The spherical punch-sided tool set prevents any harm of the punch-sided ductile material. The cutting die initialises a crack in the die-sided material with limited formability. This paper presents detailed studies on the mechanical behaviour of state of the art multi-stage clinching with cylindrical and tapered pre-hole under quasistatic and fatigue testing methods to evaluate the influence of the interlock. These results were compared to the single-stage shear-clinching technology to derive further recommendations.
CRIS-Team Scopus Importer:2023-03-29
Keywords: Aluminium alloys; High strength steels; Laboratory for material and joining technology; university of paderborn; paderborn; germania.; vehicle bodies; Mechanical fastening; Nonwelded joints

Prototype Manufacturing of Helical Needles for Suture in Deep Wound Cavities - Plettke, Raoul; Vipavc, Daniel; Grüner, Martin; Hagenah, Hinnerk; Merklein, Marion (Proc. 1st Int.Conf. Design and Processes for medical devices PROMED, 2012)
LFT Import::2019-08-05 (1837)

Prozessangepasste Lösungen für den Einsatz von Leichtbauwerkstoffen in der Blechumformung - Celeghini, Martino; Kerausch, Michael; Kreis, Oliver; Merklein, Marion; Geiger, Manfred (Robuste, verkürzte Prozessketten für flächige Leichtbauteile. Tagungsband zum Industriekolloquium 2003 des SFB 396, Erlangen, 15.-16.10, 2003)
LFT Import::2019-08-05 (960)

Prozessfenster zur Verarbeitung alternativer Stahlgüten im Presshärtprozess - Merklein, Marion; Svec, Thomas (7. Erlanger Workshop Warmblechumformung, 2012)
LFT Import::2019-08-05 (1841)

Prozesskettenverkürzung in der Blechumformung - Merklein, Marion; Geiger, Manfred; Blankl, Andreas; Cojutti, Massimo; Vogt, Uwe (Robuste, verkürzte Prozessketten für flächige Leichtbauteile. Tagungsband zum Industriekolloquium des SFB 396, 2006)
LFT Import::2019-08-05 (1283)

Prozessorientierte Werkstoffcharakterisierung für die numerische Auslegung von Blechumformperationen - EFB-Forschungsbericht Nr. 484 - Merklein, Marion; Lenzen, Matthias; Brosius, Alexander; Kuesters, Niklas (Europäische Forschungsgesellschaft für Blechverarbeitung e.V., 2018)
Die realitätsnahe Abbildung des Werkstoffverhaltens ist ein wichtiger Aspekt der numerischen Prozessauslegung mit Hilfe der Finiten-Element-Methode. Mit den Werkstoffen AA5182, AA6016, DC06, DX54 sowie DP600 werden ein tiefziehdominierter Kreuznapf und ein streckziehdominierter Stützträger numerisch und experimentell untersucht. Die entwickelte Parameteridentifikation verbessert die Abbildungsgenauigkeit für Stahlwerkstoffe, die in Versuchen einen stark umformgradabhängigen Verlauf der Anisotropie aufweisen. Zur Bewertung werden die Größen Blechdickenverteilung und Flanscheinzug herangezoge
Keywords: Werkstoffcharakterisierung; Blechumformung

Qualification of a new test for wear investigation on coated tools - Schrader, Tobias; Merklein, Marion; Engel, Ulf (Proc. 4th Int. Conf. on Tribology in Manufacturing Processes (ICTMP), 2010)
LFT Import::2019-08-05 (203)

Qualification of Laser Based Additive Production for Manufacturing of Forging Tools - Junker, Daniel; Hentschel, Oliver; Schmidt, Michael; Merklein, Marion (Journal of Manufacturing Review, 2015)
Mass customization leads to very short product life cycles, so the costs of a tool have to be amortized with a low number of workpiecesEspecially for highly loaded tools, like those for forging, that leads to expensive productsTherefore more economical production processes for tool manufacturing have to be investigatedAs laser additive manufacturing is already used for the production of moulds for injection moulding, this technology maybe could also improve the forging tool productionWithin this paper laser metal deposition, which is industrially used for tool repair, will be investigated for the use in tool manufacturingTherefore a mechanical characterization of parts built with different laser process parameters out of the hot work tool steel 1.2709 is made by upsetting tests and hardness measurementsSo the influence of the additive manufacturing process on the hardness distribution is analysed
LFT Import::2019-08-05 (2110)

Reibrührschweißen - Innovativ in der festen Phase verbinden - Geiger, Manfred; Merklein, Marion; Giera, Artur (Zeitschrift für wirtschaftlichen Fabrikbetrieb, 2005)
LFT Import::2019-07-16 (1241)

Reibungsreduzierung in EHD-Kontakten durch mikrostrukturierte Bauteiloberflächen - Auslegung, Gestaltung und umformtechnische Herstellung - Tremmel, Stephan; Marian, Max; Zahner, Michael; Weschta, Martin; Engel, Ulf; Wartzack, Sandro; Merklein, Marion (58. Tribologie-Fachtagung. 2017, Son-derband Abschlusskolloquium „Ressourceneffiziente Konstruktionselemente“ SPP 1551 der DFG, 2017)
Gezielt eingebrachte, definierte Oberflächenmikrostrukturen bieten in elastohydrodynamischen (EHD) Kontakten Potential zur Reibungsreduzierung und können damit die Energieeffizienz technischer Systeme erhöhen. Um die größtmögliche Wirksamkeit zu erreichen, sind diese Oberflächenmikrostrukturen auf die jeweilige Anwendung abzustimmen. Die Realisierung theoretisch genauer Mikrostrukturen ist zudem durch die Fertigungstechnik limitiert. Des Weiteren bestimmt das Verschleißverhalten der Mikrostrukturen im Einsatz die Bauteillebensdauer. Für einen wirksamen Einsatz über den gesamten Produktlebenszyklus hinweg bedarf es somit eines grundlegenden Verständnisses der Zusammenhänge zwischen Gestaltung, Herstellung und Einsatzverhalten oberflächenstrukturierter Bauteile. Vor diesem Hintergrund werden im vorliegenden Beitrag ein Simulationsansatz zur Untersuchung der Wirkweise von Oberflächenmikrostrukturen vorgestellt sowie eine Methodik abgeleitet, die die systematische Auslegung und Gestaltung von Oberflächenstrukturen erlaubt. Die Methodik erlaubt die Berücksichtigung individueller tribologischer Belastungskollektive und fertigungstechnischer Restriktionen. Die Fertigungsrestriktionen bei der Strukturerzeugung wurden im Hinblick auf industrielle Maßstäbe für einen Mikroprägeprozess ermittelt. Auf Basis tribologischer Untersuchungen auf einem Nocken/Stößel-Komponentenprüfstand erfolgt die Beurteilung des Reibungs- und Verschleißverhaltens der mikrostrukturierten Bauteil
LFT Import::2019-08-05 (2259)
Keywords: Elastohydrodynamik; Mikrostrukturen; Mikroprägen

Relevanzanalyse zur Berücksichtigung der kinematischen Verfestigung in Tiefziehprozessen mit geschlossenem Profil - Lafarge, Rémi; Ahmed, Usama; Brosius, Alexander; Lenzen, Matthias; Jäckisch, Manuel; Merklein, Marion (Europäische Forschungsgesellschaft für Blechverarbeitung e.V., 2021)
In diesem Forschungsprojekt wird ein kinematischer Indikator entwickelt, der auf der Basis einer isotropen FE-Simulation den möglichen Fehler aufgrund der Nichtbeachtung der kinematischen Verfestigung während des Umformprozesses ermittelt. Dieser Indikator kann in frühen Machbarkeitsstudien eingesetzt werden, ohne dass die notwendige Werkstoffcharakterisierung im Vorfeld durchgeführt werden muss. Auf diese Weise können das Produkteinführungsrisiko und die Entwicklungskosten minimiert werden. Im vorliegenden Projekt wird der Einfluss nichtlinearer Dehnpfade mit Hilfe von Tiefzieh- und Streifenzugbiegeversuchen untersucht. Anschließend werden die komplexen nichtlinearen Dehnpfade mit Hilfe eines an der Professur Formgebende Fertigungsverfahren, TU Dresden, entwickelten Indikators analysiert, wobei die experimentellen Ergebnisse mit dem Indikator verglichen werden, der den Einfluss des Modells der kombinierten Verfestigung im Gegensatz zum rein isotropen oder kinematischen Materialmodell vorhersagt. Um das angestrebte Ziel zu erreichen, ist das laufende Projekt in drei Teile gegliedert. Zunächst werden Experimente für zwei verschiedene Tiefziehverfahren und das Streifenzugbiegeverfahren durchgeführt. Diese Prozesse werden dann in LS-DYNA mit verschiedenen Verfestigungsgesetzen simuliert, die ein vollständig isotropes, ein kombiniertes und ein vollständig kinematisches Materialmodell umfassen. Die in den Experimenten gemessenen geometrischen Eigenschaften werden dann mit verschiedenen simulierten Verfestigungsmodellen verglichen. Anschließend wird der Einfluss der kinematischen Verfestigung mit Hilfe eines analytischen Indikators analysiert, der die Bereiche zeigt, die am stärksten von der kinematischen Verfestigung beeinflusst werden und der auch den Unterschied der Zielwerte als Ergebnis des isotropen und kombinierten Verfestigungsgesetzes anzeigt. Die in diesem Projekt durchgeführten Arbeiten und Ergebnisse umfassen: Extrahieren der geometrischen Parameter, die Biegewinkel für U-Profil-Proben, Biegeradius für streifenzugbiegeumgeformte Proben und Blechdicke für Kreuznapf-Proben umfassen, zum Vergleich mit drei verschiedenen Verfestigungsgesetzen; Untersuchung des Einflusses der kinematischen Verfestigung als Folge eines nichtlinearen Dehnungsweges mit Hilfe eines analytischen Indikators. Die FE-Simulationen zeigen, dass die aus dem Modell des kombinierten Verfestigungsmaterials extrahierten Ergebnisse den experimentellen Ergebnissen für Tiefzieh-, Streifenzugbiege- und Kreuznapf-Proben weitaus näherkommen. Darüber hinaus ist es mit den Indikatorberechnungen gelungen, die Bereiche vorherzusa-gen, die anfällig für eine Beeinflussung durch die kinematische Verfestigung sind. Solche Regionen werden durch höhere bzw. niedrigere Werte des kinematischen Indikators repräsentier

Research activities in field of materials forming behaviour and failure mechanisms - Merklein, Marion; Kuppert, Andreas; Biasutti, Manfredi; Lupino, Roberto (testXpo - 18. International Forum for Materials Testing (19.10.2009), 2009)
LFT Import::2019-08-05 (200)

Researching of commonalities and differences in cold forging of spur and helical gears - Kiener, Christoph; Merklein, Marion (Production Engineering, 2019)
Modern automobiles are equipped with a large number of gear transmissions. In the powertrain, for example, they are used as multi-stage manual transmissions and in the interior for mirror and seat adjustment. Machining manufacturing processes—like gear hobbing and shaping—represent the state of the art in gear manufacturing due to high manufacturing accuracy and flexible machining possibilities. With regard to economic, ecological and technical aspects, cold forging offers a promising production technology. In conventional transverse and forward extrusion processes, the ejection process is a challenge due to high forces and a negative influence on the gearing accuracy. One variant of forward extrusion is the so-called “Samanta” process, whereby an additional ejection step is avoidable by sequential forming of the gears. For the establishment of this process in industry, the increase of the achievable gearing accuracy and the achievable tool life is of major relevance. Thus, a deeper process understanding as well as knowledge about the influences on the process results is beneficial. In this context, the aim of this research work is to produce spur and helical gears by the “Samanta”-process. In addition to the resulting component properties, the characteristics of the process are determined. On this basis, commonalities and differences in cold forging of spur and helical gears are investigated to gain a principle process understanding. These findings are also used to derive possible approaches for improving component and process properties in future research work. The results reveal that cold forging of spur and helical gears by the “Samanta”-process results in characteristic properties and specific challenges within the gear types. Furthermore, a geometric adaptation in the gearing area of the used die promises enormous potential for a positive influence on the process results for both types of gearing.
CRIS-Team Scopus Importer:2019-05-24
Keywords: Cold forging; Gears; Tool

Research of Adapted Tool Design in Cold Forging of Gears - Kiener, Christoph; Merklein, Marion (International Journal of Material Forming, 2019)
LFT Import::2019-07-29 (2383)

Residual effects of ultrasonic assistance in metal forming - Jäckisch, Manuel; Merklein, Marion (1st International Conference on Engineering Manufacture 2022 (EM 2022), 2022)
Characterized by a high material utilization and short cycle times, cold forming processes enable a high efficient and an environmentally compatible production. Nevertheless, an increasing use of high strength materials and a growing demand for complex part geometries pose new challenges to well established forming operations. Thus, there is a demand for innovative processes and process adaptions that extend existing process ranges. A promising measure is the application of ultrasonic assistance. Superimposing a high frequency oscillation to the forming process leads to an immediate material softening, enabling a significant reduction of the process forces. Even though this softening effect is well known and has been addressed in several investigations, the underlying mechanisms remain subject of current research. Besides this temporary softening, there are also residual effects, indicating a permanently altered material state after ultrasonic assistance. Present studies indicate both, residual hardening and softening in the context of ultrasonic-assisted forming. The goal of this contribution is an in-depth analysis of the influence of ultrasonic assistance in metal forming with regard to residual effects. This contributes to clarifying the underlying mechanisms. Therefore, stepwise ultrasonic-assisted compression tests with varying amplitudes and oscillation interval durations are carried out. Focusing on the strain hardening, particular interest is given to variances of the strain hardening exponent as well as the resulting hardness after forming. By comparing the results to conventional compression tests, ultrasonic-induced effects are determined. Moreover, by means of the stepwise conducted experiments the influence on the microstructure is determined for different strain conditions.<br
Keywords: ultrasonic; metal forming; copper; brass

Residual effects of ultrasonic-assisted compression testing on pure copper - Jäckisch, Manuel; Michalski, Markus; Merklein, Marion (AIP Conference Proceedings, 2019)
Due to the rising demand for weight and volume reduction, the usage of high strength materials becomes more and more common. Regarding process forces, the application range of existing presses is limited in forming such metals. One approach to reduce the process forces considerably is superimposing the tool movement with ultrasonic vibration. Although the immediate occurring force and mean stress reduction were first discovered in 1955 by Langenecker and Blaha and are known phenomena, underlying effects of ultrasonic-based material softening remain object of current research. Prominent theories explaining the acoustic softening are stress superposition as well as surface and volume effects. By carrying out ultrasonic-assisted compression tests with 20 kHz oscillation frequency on pure copper, this study intends to determine permanently altered material characteristics. Therefore, compression testing with varying oscillation interval as well as amplitude is conducted and force-displacement-curves are analyzed. In comparison to conventional upsetting, an initial softening effect occurs after the unique presence of ultrasonic-assistance. Moreover, metallographic analyses support former findings. With regard to the examination of material flow as well as grain deformation, permanent microstructure alteration is found. In this way, temporary process-related and permanent material-induced effects are separated.
CRIS-Team Scopus Importer:2019-07-23

Review on mechanical joining by plastic deformation - Meschut, Gerson; Merklein, Marion; Brosius, Alexander; Drummer, Dietmar; Fratini, Livan; Füssel, Uwe; Gude, Maik; Homberg, Werner; Martins, Paulo A. F.; Bobbert, Mathias; Lechner, Michael; Kupfer, Robert; et al. (Journal of Advanced Joining Processes, 2022)
Mechanical joining technologies are increasingly used in multi-material lightweight constructions and offer opportunities to create versatile joining processes due to their low heat input, robustness to metallurgical incompatibilities and various process variants. They can be categorised into technologies which require an auxiliary joining element, or do not require an auxiliary joining element. A typical example for a mechanical joining process with auxiliary joining element is self-piercing riveting. A wide range of processes exist which are not requiring an auxiliary joining element. This allows both point-shaped (e.g., by clinching) and line-shaped (e.g., friction stir welding) joints to be produced. In order to achieve versatile processes, challenges exist in particular in the creation of intervention possibilities in the process and the understanding and handling of materials that are difficult to join, such as fibre reinforced plastics (FRP) or high-strength metals. In addition, predictive capability is required, which in particular requires accurate process simulation. Finally, the processes must be measured non-destructively in order to generate control variables in the process or to investigate the cause-effect relationship. This paper covers the state of the art in scientific research concerning mechanical joining and discusses future challenges on the way to versatile mechanical joining processe
Keywords: Mechanical Joining; Joining processes; Pin-Joining; Clinching; Self-piercing riveting; Versatility

Robot-assisted surface treatment strategies of AA6014 sheet metal for accumulative roll bonding - Zettl, Bastian; Merklein, Marion (ESAFORM 2021 - 24th International Conference on Material Forming, 2021)
The application of high strength aluminum sheet metal components in automotive and aviation products effectively saves material and thus weight. Material strengthening can be realized by accumulative roll bonding (ARB), which belongs to the severe plastic deformation processes. Through repeated rolling steps a multilayered sheet metal is produced, which possesses increased strength due to its ultra-fine grained microstructure. Prior to each rolling step a surface treatment via wire brushing is mandatory for removing the oxide layer and roughening the sheet surface, which enables the bonding between the unique layers during rolling. The necessary surface treatment of the sheets is not fully understood by the current state of the art. In the past, it was not possible to achieve a defined and stable surface finish, because the brushing operation was done manually. The improvement of the process stability is essential to determine the relationship between the input parameters for brushing and the resulting bond strength of multilayered ARB sheets. For this reason, a robot-controlled surface treatment is introduced. The investigated material is the precipitation-hardened aluminum AA6014 with a sheet thickness of 1 mm. A suitable brushing kinematic under constant load is implemented and its effects on the surface properties are investigated by roughness measurements. The investigation shows, that the parameter combination leads to comparable or even higher roughness values than through manual brushing. Through 16 consecutive brushing paths a homogeneous and sufficient high surface roughness is realized, which enables material bonding in the rolling step. Thus, the research results indicate, that the robot-assisted surface treatment of ARB sheet metal is a promising method for a better automation and reproducibility of the brushing and the overall ARB process.
CRIS-Team Scopus Importer:2021-11-26
Keywords: Accumulative roll bonding; Robot-assisted brushing; Roughness; Surface treatment

Robustness Analysis of Pin Joining - Römisch, David; Zirngibl, Christoph; Schleich, Benjamin; Wartzack, Sandro; Merklein, Marion (Journal of Manufacturing and Materials Processing, 2022)
The trend towards lightweight design, driven by increasingly stringent emission targets, poses challenges to conventional joining processes due to the different mechanical properties of the joining partners used to manufacture multi-material systems. For this reason, new versatile joining processes are in demand for joining dissimilar materials. In this regard, pin joining with cold extruded pin structures is a relatively new, two-stage joining process for joining materials such as high-strength steel and aluminium as well as steel and fibre-reinforced plastic to multi-material systems, without the need for auxiliary elements. Due to the novelty of the process, there are currently only a few studies on the robustness of this joining process available. Thus, limited statements on the stability of the joining process considering uncertain process conditions, such as varying material properties or friction values, can be provided. Motivated by this, the presented work investigates the influence of different uncertain process parameters on the pin extrusion as well as on the joining process itself, carrying out a systematic robustness analysis. Therefore, the methodical approach covers the complete process chain of pin joining, including the load-bearing capacity of the joint by means of numerical simulation and data-driven methods. Thereby, a deeper understanding of the pin joining process is generated and the versatility of the novel joining process is increased. Additionally, the provision of manufacturing recommendations for the forming of pin joints leads to a significant decrease in the failure probability caused by ploughing or buckling effects.
CRIS-Team Scopus Importer:2022-11-04
Keywords: joining by forming; pin joining; robustness analysis; versatile joining process

Robust, shortened process sequences for sheet light weight parts - Geiger, Manfred; Merklein, Marion; Kerausch, Michael; Celeghini, Martino (Proceedings of the 5th International Conference on Industrial Tools, 2005, Velenje, Slowenien, 2005)
LFT Import::2019-08-05 (1177)

Scale-up of Innovative Forming Solutions from Scientific Fundamentals to Industrial Applications - Merklein, Marion; Lechner, Michael; Böhm, W.; Degner, Julia (2016)
LFT Import::2019-08-05 (2219)

Selective application of different forming temperatures for individual process stages in a rivet manufacturing process with high nitrogen steel - Kuball, Clara-Maria; Uhe, Benedikt; Meschut, Gerson; Merklein, Marion (2nd International Conference on Advanced Joining Processes, 2021)

Self-piercing riveting using rivets made of stainless steel with high strain hardening - Uhe, Benedikt; Kuball, Clara-Maria; Merklein, Marion; Meschut, Gerson (Forming the Future - Proceedings of the 13th International Conference on the Technology of Plasticity. The Minerals, Metals & Materials Series., 2021)

Shear-Clinching of Multi-Element Specimens of Aluminium Alloy and Ultra-High-Strength Steel - Han, Daxin; Hörhold, Réjane; Müller, Martin; Wiesenmayer, Sebastian; Merklein, Marion; Meschut, Gerson (Key Engineering Materials, 2018)
The newly developed joining-by-forming technology "shear-clinching", features a potentially single-stage process for joining UHSS without requiring any additional elements. Foundational studies have focused on the functionality of shear-clinching at a one-element sample. To ensure the safety of the industrial application of the shear-clinching technology, an investigation with component-like samples with several joints is required. This paper presents a detailed analysis of the material behaviour during the shear-clinching process with multi-element specimens to evaluate the influence of the neighbouring joints. In order to describe the influence of the neighbouring joints, the deformations resulting from the bending and material displacement are recorded without contact after the joining process: locally around the joining point and globally over the entire sample size. To minimize such bending effects, a tool-sided adaptation is provided. The results show the high potential of shear-clinching joining by UHSS and give further recommendations for future multi-material application.
LFT Import::2019-07-29 (2302)
Keywords: Clinching; Joining by forming; Lightweight; Multi-element specimen; Multi-material mix

Shear-clinching of the high-strength aluminum alloy AA7075 with laser-assisted retrogression - Wiesenmayer, Sebastian; Merklein, Marion (Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2022)
Due to their extraordinarily high specific strength, aluminum alloys of the 7000 series are coming into focus of car manufacturers. In an aged state, the limited formability of the alloys poses a challenge for joining by forming processes, which are of particular importance for the realization of multi-material lightweight structures. The innovative shear-clinching technology has proven to be suitable for joining die-sided high-strength steels and punch-sided aluminum alloys. Yet, the process is limited by the formability of the upper joining partner. Due to the high strength of AA7075 in the artificially aged T6 temper, the material flow is obstructed during the joining sequence and failure occurs. The formability of the hardenable alloy can be enhanced by the performance of short-term heat treatment prior to joining. For this purpose, a laser is a suitable heat source, allowing the effective heating of small areas. Within this study, the influence of the temperature during the heat treatment with a diode laser on the material properties of AA7075 is investigated by uniaxial tensile tests and metallographic analyses. Moreover, the joinability of the alloy as well as the resulting joint formation and strength in dependence on the process control during the heat treatment are analyzed. Softening of the alloy enhances with increasing heat treatment temperatures. However, in comparison to the T6 temper, the ductility does not increase. For temperatures of 300 degrees C and higher, the joinability of AA7075 after the heat treatment is given. Still, for 300 degrees C cracks are initiated, compromising the joint quality. Despite the occurrence of cracks, the highest joint strength is achieved after a heat treatment at 300 degrees C, as for higher temperatures, the material's strength becomes distinctly lower.
CRIS-Team WoS Importer:2022-12-23

Sheet-Bulk Metal Forming - Gröbel, Daniel; Schneider, Thomas; Merklein, Marion (60 Excellent Inventions in Metal Forming, 2015)
Sheet-Bulk Metal Forming (SBMF) is an innovative class of forming processes which enables the manufacturing of functional components out of sheet metal. This is achieved by the application of sheet and bulk forming operations on sheets of 1 to 5 mm initial thickness with an intended three dimensional material flow. SBMF products are characterized by profound functional integration and subsequently possess a high lightweight potential. In contrast to alternative production technologies, SBMF formed products feature the advantage of improved mechanical properties due to strain hardening and an unbroken fiber course. Furthermore the possibility to produce high accuracy netshaped parts in mass production with a shortened process chain qualifies SBMF as adequate method to meet present and future demands of production.
LFT Import::2019-08-05 (2073)

Sheet-bulk metal forming – forming of functional components from sheet metals - Merklein, Marion; Gröbel, Daniel; Löffler, Maria; Schneider, Thomas; Hildenbrand, Philipp (Proceedings of the 4th International Conference on New Forming Technology, 2015)
LFT Import::2019-08-05 (2116)

Sheet-Bulk Metal Forming of Preformed Sheet Metal Parts - Schneider, Thomas; Merklein, Marion (Key Engineering Materials, 2011)
Due to ecological and economic challenges there is a rising demand on closely-tolerated complex functional components. Regarding short process chains and improved mechanical properties conventional forming processes are often limited. A promising approach to meet these requirements can be seen in the combination of traditional sheet and bulk metal forming processes, to form sheet metals out of the sheet plane with typical bulk forming operations. The challenge of applying conventional bulk forming operations on sheet metal is the interaction between regions of high and low deformation, which is largely unknown in literature. To analyze this topic fundamentally, a process combination of deep drawing and upsetting is developed for manufacturing tooth-like elements at pre-drawn cups. To fully understand material flow out of the sheet plane into the tooth cavity and to identify and qualify process factors depending on the functional elements' geometry and friction, a single upsetting stage forming a simplified model of the blank is virtually analyzed with finite-element simulation. By inhibiting the forming history of the pre-drawn blank, the upsetting process can be investigated without interactions with a previous deep drawing operation. © (2011) Trans Tech Publications.
LFT Import::2019-07-29 (1634)
Keywords: Deep drawing; Finite element simulation; Sheet-bulk metal forming; Upsetting

Sheet-bulk metal forming - potential and challenges of a new class of forming processes - Schneider, Thomas; Merklein, Marion (Proceedings of PLASTICITY ’15: The Twenty First International Symposium on Plasticity and its Current Applications, 2015)
LFT Import::2019-08-05 (2052)

Sheet-Bulk Metal Forming Processes - State of the Art and its Perspectives - Merklein, Marion; Hagenah, Hinnerk; Schneider, Thomas (TTP 2013 - Tools and Technologies for Processing Ultra High Strength Materials, 2013)
LFT Import::2019-08-05 (1907)

Sheet Hydroforming: Analytical Modeling and Experimental Verification of Complex Structures - Geiger, Manfred; Merklein, Marion; Tolazzi, Massimo (Production Engineering - Annals of the WGP, 2005)
LFT Import::2019-08-05 (1233)

Sheet metal forming - a new kind of forge for the future - Geiger, Manfred; Merklein, Marion (Key Engineering Materials, 2007)
Within the last years in sheet metal forming a trend towards forming at elevated temperatures as well as temperature assisted forming technologies can be observed. This development is caused by the increasing need on light and high strength materials in order to fulfill the demands of light weight structures. The decision which kind of temperature assistance is the most useful in order to improve the formability of the material depends on a hugh number of process influencing parameters, like e.g. the material itself, the geometry of the component, the number of forming operations etc.. In this paper the general possibility to separate different temperature assisted forming processes with regard to the used materials will be introduced. The different forming procedures will be explained and discussed. Examples with an industrial relevance are shown.
LFT Import::2019-07-16 (1467)
Keywords: Elevated temperature; Hot stamping; Sheet metal forming

Sheet metal forming limits as classification problem - Jaremenko, Christian; Huang, Xiaolin; Affronti, Emanuela; Merklein, Marion; Maier, Andreas (Proceedings of the 15th IAPR International Conference on Machine Vision Applications, 2017)
Forming limit diagrams are used to evaluate the formability of metal sheets and describe the maximum strain to failure in terms of major and minor strain. The main idea is the detection of the onset of necking in limited areas of the investigated sheet metals. Current methods introduce location-or time-dependency or may require user interaction. Within this contribution we interpret the onset of necking as classification problem and show that a support vector machine performs comparable to a human experts group. Best results reach up to 87.5 % avg. precision and 84.9 % avg. recall, using all available 2D-information, while being time- and location-independent.
UnivIS-Import:2017-12-18:Pub.2017.tech.IMMD.IMMD5.sheetm

Short Term Effects of Laser Forming in Aluminium Alloys - Geiger, Manfred; Merklein, Marion (Production Engineering, 2000)
LFT Import::2019-07-15 (772)

Simulation-Based Determination of Deflection Characteristic of Tooling System and its Modeling in FE Simulation of Cold Forging Process - Kroiß, Thomas; Engel, Ulf; Merklein, Marion (Steel Research International, 2010)
LFT Import::2019-08-05 (722)

Simulation-Based Investigation of the Heat Exchange Within a Partial Hot Stamping Process - Reihani, Alborz; Badroosian, Darwin; Heibel, Sebastian; Schweiker, Thomas; Merklein, Marion (Lecture Notes in Mechanical Engineering, 2024)
Studies on crash performance show that hot stamped components with homogeneous mechanical properties can reach their limits in highly stressed car body areas. To face this challenge, hot stamped components can be optimized by integrating ductile areas. A suitable technology for adjusting tailored properties is based on a special furnace chamber within a multi-chamber furnace in which a cooled aluminum mask protects the blank locally from incident heat radiation. Simultaneously, the mask absorbs the blank’s own radiation. In addition to the temperature and radiation properties, this heat exchange depends in particular on the orientation and position of the radiating surfaces in the furnace chamber. For this reason, the mask distance to the blank can influence the width and characteristics of the transition zone after partial hot stamping. In order to predict the correlation between hard and ductile area, the process of partial hot stamping with varying mask distances is modelled in LS-DYNA® and validated experimentally. The results indicate that it is feasible to simulate the influence of the mask distance on the resulting hard, soft and transition zone after partial hot stamping. Furthermore, the results demonstrate that transition zones on a partially hot stamping part can be designed more flexibly, thus extending the limits in terms of part complexity.
CRIS-Team Scopus Importer:2023-10-20
Keywords: Finite-Element Simulation; Heat Treatment; Hot Stamping; Tailored Properties

Simulation der Werkzeuglebensdauer bei Ermüdungsversagen - Killmann, Martin; Merklein, Marion (36. Jahrestreffen der Kaltmassivumformer 2023, 2023)
Wie funktioniert eine Lebensdauerberechnung? Welche Materialparameter werden dafür benötigt? Wie können Materialparameter experimentell ermittelt werden? Wie kann eine Lebensdauersimulation in der Praxis eingesetzt werden?<br

Simulation of a Full Forward Extrusion Process from Metal Strip - Merklein, Marion; Stellin, Tommaso; Engel, Ulf (AIP Conference Proceedings, 2011)
The interest on mass production of small complex metal components is currently fostered by fields like electronics and micromechanics. A possible approach is seen in a multi-step bulk forming process, limited among scaling problems by handling difficulties between the forming stages. A radical simplification of the positioning of the workpiece is seen in a process in which a metal strip acts both as raw material and support of the workpiece through the different forming stages. Within the study of this method, a full forward extrusion process from metal strip has been simulated with the goal of getting the basic knowledge about the strip behavior and process performance. The influence of the main geometric and tribological features has been evaluated designing a full factorial plan. The role of the radius of curvature of the tool edges and of the factor of friction have become the points of main interest in the optimization of the process. © 2011 American Institute of Physics.
LFT Import::2019-07-29 (1636)
Keywords: full forward extrusion; metal strip forming; microforming

Simulationsbasierte Untersuchung eines neuartigen Fügekonzepts für Rotoren elektrischer Maschinen - Frey, Philipp; Hildering, Sven; Tsoupis, Ioannis; Stellin, Tommaso; Merklein, Marion (Tagungsband 17. RoundTable - Simulating Manufacturing, 2016)
LFT Import::2019-08-05 (2171)

Simulationsgestützte Auslegung maßgeschneiderter wärmebehandelter Aluminiumhalbzeuge - Merklein, Marion; Hagenah, Hinnerk; Lechner, Michael; Kuppert, Andreas (16. Workshop Simulation in der Umformtechnik, 2013)
LFT Import::2019-08-05 (1886)

Size effects of CuZn37 brass foil in microforming - Li, He Zong; Dong, Xiang Huai; Wang, Qian; Shen, Yu; Diehl, Alexander; Hagenah, Hinnerk; Engel, Ulf; Merklein, Marion (Cailiao Kexue yu Gongyi/Material Science and Technology, 2011)
Uniaxial tensile tests and microbending experiments of brass foil specimens are performed to investigate size effects of metal foils in microforming process. The specimens are annealed at two different temperatures to obtain fine and coarse grain structure. In the paper, the springback angle in microbending process is predicted based on the classical plasticity theory and strain gradient theory. In uniaxial tensile tests, the increasing of material strength with decreasing foil thickness is observed, which indicates obvious presence of size effects for CuZn37 brass foils, especially for coarse grain specimens. In microbending experiments, obvious size-dependences of springback angle are observed, in which the springback angle of metal foils is increasing with foil thickness decreasing. The reasons for these size effects are discussed and the strain gradient hardening is important to microforming process.
LFT Import::2019-07-29 (1792)
Keywords: CuZn37 brass foil; Microforming; Size effect; Springback angle; Strain gradient

Size effects on springback behaviors due to plastic strain gradient hardening in microbending process of pure aluminum foils - Li, Hezong; Dong, Xianghuai; Shen, Yu; Diehl, Alexander; Hagenah, Hinnerk; Engel, Ulf; Merklein, Marion; et al. (Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2010)
In order to investigate the springback behavior of pure aluminum foils, scaled microbending experiments with different thicknesses ranging from 25μm to 500μm were carried out. In the experiments, it is observed that springback angle increases with decreasing foil thickness, which indicates obvious presence of size effects, and is attributed to plastic strain gradient hardening. So a constitutive model, taking into accounts both plastic strain and plastic strain gradient hardening, is proposed to analyze the microbending process of thin foils. The model is based on the relationship between yield stress and dislocation density, and is adopted to predict the springback angle after microbending both by analytical expressions and by FE simulation. It is confirmed that the predictions by using the proposed hardening model agree well with the experimental data, while those by using conventional elastoplastic model cannot capture such size effects. © 2010.
LFT Import::2019-07-02 (132)
Keywords: Microbending; Plastic strain gradient; Size effect; Springback

Smart FE-based tool design in cold forging - Andreas, Kolja; Kiener, Christoph; Engel, Ulf; Merklein, Marion (Advanced Materials Research, 2014)
In cold forging, the forming tool takes a key role. The present study focuses on the FE based analysis of different die sided leverages on the stress state in and the elastic behaviour of the forming tool. The results reveal a great influence of the workpiece material and the tool layout on the outcome of the forming process and the corresponding tool stresses.
LFT Import::2019-07-29 (2046)
Keywords: Cold forging; Design optimization; Tool

Sonderverfahren zur Magnesiumverarbeitung - Merklein, Marion (Tagungsband MEFORM 2006, 29.-31. März 2006, Freiberg, 2006)
LFT Import::2019-08-05 (1303)

Specimen for a Novel Concept of Biaxial Tension Test? Design and Optimisation - Hußnätter, Wolfgang; Merklein, Marion; Geiger, Manfred (Advanced Methods in Material Forming, 2007)
Although in times of highest significance of process modelling and numerical simulation yield loci get more and more important, these characteristic values do only exist for a few materials primarily at room temperature. In this paper a novel concept of an experimental setup is introduced, with which plastic yielding of sheet metal can be examined also at elevated temperatures. The design of specimen is of great importance for the quality of experimental results, because stress conditions and with it forming behaviour are constituted. Thus, it must be optimized in consideration of stress singularities at corners and for achieving stress states, which are comparable to those of previous yield locus examinations. Most information and details can be obtained from finite element simulation. © 2007 Springer-Verlag Berlin Heidelberg.
LFT Import::2019-07-16 (1389)
Keywords: FE-simulation; sheet metal forming; yield locus

Specimen for a novel concept of the biaxial tension test - Geiger, Manfred; Hußnätter, Wolfgang; Merklein, Marion (Journal of Materials Processing Technology, 2005)
LFT Import::2019-07-16 (1191)
Keywords: Biaxial testing; FE-simulation; Sheet metal

Specimen´s Geometry Related Influences on Load-Bearing Capacity of Joining Aluminium and UHSS by Innovative Shear-Clinching - Hörhold, Réjane; Müller, Martin; Merklein, Marion; Meschut, Gerson (Journal of Materials Science Research, 2017)
LFT Import::2019-07-29 (2243)

Stability of Bipolar Plate Materials for Proton-Exchange Membrane Water Electrolyzers: Dissolution of Titanium and Stainless Steel in DI Water and Highly Diluted Acid - Fiedler, Lena; Ma, Tien Ching; Fritsch, Birk; Risse, Jan Henning; Lechner, Michael; Dworschak, Dominik; Merklein, Marion; Mayrhofer, Karl; Hutzler, Andreas (ChemElectroChem, 2023)
The widespread use of proton exchange membrane water electrolyzers (PEMWE) is hindered by their high cost, of which a colossal factor is caused by the bipolar plates (BPP). In this paper, we investigate the stability of two BPP materials on-line with an optimized scanning flow cell setup coupled to an inductively coupled plasma mass spectrometer (SFC-ICP-MS), as well as scanning electron microscopy (SEM). The stability of currently used titanium and a cheaper alternative, stainless steel (SS) 316L, were characterized in deionized (DI) water and 0.5 mM H2SO4 to mimic the conditions at the BPP under operation. We show that the dissolution of Ti is negligible, whereas SS 316L degrades notably. Here, besides pH, the applied potentials play a crucial role. Nonetheless, even for the highest measured dissolution rate of SS 316L, the contamination in a full cell is estimated to remain below 1 ppm. This work illustrates the capabilities of on-line high-throughput stability tests for BPP materials and could therefore contribute towards optimization of cost-effective PEMWE.
CRIS-Team Scopus Importer:2023-09-29
Keywords: Cyclic voltammetry; Stability; Stainless Steel; Titanium; Water splitting

Stability of forming induced residual stresses in stainless steel components under mechanical load - Jobst, Andreas; Merklein, Marion (Manufacturing Letters, 2023)
Cold forward extrusion leads to the generation of residual stresses, which can have an advantageous or detrimental effect on the operating behavior of the formed components. In industrial practice, energy-intensive annealing steps are often used to remove unknown stress states and thus prevent unexpected failures. Residual stress-related knowledge can therefore help to save energy and resources. To be able to estimate the effects, not only sign and magnitude need to be known, but also the residual stress stability under typical operating loads. In this paper, stainless steel X6Cr17 (DIN 1.4016, AISI 430) is formed by forward rod extrusion at room temperature. The forming process leads to residual stresses in the formed components, which are subsequently subjected to mechanical testing. To represent different initial states, components with varied die opening angles are produced and tested. A modified 3-point bending setup is used to generate a defined tensile load stress in the part surface. The results show a behavior of the residual stresses, which is depending on the load magnitude, the initial stress state and the work hardening distribution in the part. While the number of cycles has an influence, the largest changes occur in the first stroke.
CRIS-Team Scopus Importer:2023-10-20
Keywords: Extrusion; Residual stress; Stability; Stainless steel

Stability of forming induced residual stresses in stainless steel parts at elevated temperature - Jobst, Andreas; Merklein, Marion (ICRS11 - 11th International Conference on Residual Stresses, 2023)

Stahl heiß in Form gebracht - Geiger, Manfred; Merklein, Marion; Lechler, Jürgen (Automobiltechnik in Bayern, 2007)
LFT Import::2019-07-16 (1461)

Statistical Investigations on Friction Stir Welded - Giera, Artur; Merklein, Marion; Geiger, Manfred (Sheet Metal 2005, Proceedings of the 11th International Conference on Sheet Metal, 2005)
LFT Import::2019-08-05 (1163)

Strahlbearbeitung von Fließpresswerkzeugen - Integration von Strahloperationen in den Werkzeugherstellungsprozess - Andreas, Kolja; Merklein, Marion (wt Werkstattstechnik - Online, 2016)
LFT Import::2019-07-29 (2216)

Strategies for residual stress adjustment in bulk metal forming - Franceschi, A.; Stahl, J.; Kock, C.; Selbmann, R.; Ortmann-Ishkina, S.; Jobst, Andreas; Merklein, Marion; Kuhfuss, B.; Bergmann, M.; Behrens, B. -A.; Volk, W.; Groche, P. (Archive of Applied Mechanics, 2021)
The family of bulk forming technologies comprises processes characterised by a complex three-dimensional stress and strain state. Besides shape and material properties, also residual stresses are modified during a bulk metal forming process. The state of residual stresses affects important properties, like fatigue behaviour and corrosion resistance. An adjustment of the residual stresses is possible through subsequent process steps such as heat treatments or mechanical surface modification technologies, like shot peening and deep rolling. However, these additional manufacturing steps involve supplementary costs, longer manufacturing times and harmful effects on the product quality. Therefore, an optimized strategy consists in a targeted introduction of residual stresses during the forming processes. To enable this approach, a fundamental understanding of the underlying mechanisms of residual stress generation in dependence of the forming parameters is necessary. The current state of the art is reviewed in this paper. Strategies for the manipulation of the residual stresses in different bulk forming processes are classified according to the underlying principles of process modification.
CRIS-Team Scopus Importer:2021-03-19
Keywords: Bulk forming; Cold forming; Hot forming; Manufacturing; Residual stress

Strength of self-piercing riveted joints with conventional rivets and rivets made of high nitrogen steel - Uhe, Benedikt; Kuball, Clara-Maria; Merklein, Marion; Meschut, Gerson (ESAFORM 2021 - 24th International Conference on Material Forming, 2021)

Stretch Forming of Ti-6Al-4V Hybrid Parts at Elevated Temperatures - Hafenecker, Jan; Rothfelder, Richard; Schmidt, Michael; Merklein, Marion (Sheet Metal 2021, 2021)
Keywords: Additive Manufacturing; Forming; Titanium

Study of Microforging of Parallel Ribs from Metal Strip - Stellin, Tommaso; Van Tijum, Redmer; Merklein, Marion; Engel, Ulf (Material Forming - ESAFORM 2014, 2014)
The on-going trend in product miniaturization, together with the increasing quality and reduction of costs of micro-components, leads to the need of a robust process design, which might additionally avoid the occurrence of defects in the workpiece. Processes like microforming are affected by variations which can be foreseen but not totally mastered in the design stage. One approach is seen in an adaptive control system based on a metamodel processing the data of online measuring. This approach is grounded on in-depth knowledge based on correct and precise process modelling. This paper presents both experimental and simulative study of a microforging process, part of a more complex forming chain. It consists of six parallel ribs on metal strip. The ribs have a width of 250 μm and are spaced by a gap of 150 μm. The process has been studied by different punch forces, analyzing the final geometry of the workpiece. In particular the rib height is considered as critical to quality parameter. The simulations show reliable results that can be used for the design of the model interfacing measurement and control of the whole microforming process. © 2014 Trans Tech Publications, Switzerland.
LFT Import::2019-08-05 (2040)
Keywords: Microforging; Sheet-bulk metal forming; Stainless steel

Study of the mechanical properties of sheet metals drawn through drawbeads - Schmid, Harald; Merklein, Marion (Manufacturing Review, 2019)
The use of modern materials leads to a need for detailed knowledge of the material flow. Drawbeads are one common way to control serial forming processes. Although they are already well investigated, the effect on the resulting mechanical properties after a drawbead passage is not analysed in detail yet. This work is showing the influence of a drawbead geometry used in deep drawing on typical mechanical properties. Therefore, different sheet metal materials are preloaded in a modified strip drawing test with commonly used drawbeads. In testing, three different levels of pressure between 2.5 MPa and 7.5 MPa and of drawing speed between 10 mm/s and 50 mm/s are combined to nine variations and are examined. Afterwards, specimens are cut out by a laser cutting machine of the drawn strips. Those specimens are then tested with the use of an optical measurement system. Results are discussed in relation to blankholder pressure, drawing velocity and drawbead geometry to work out the main effects. Overall it can be stated, that variations of blank holder pressure and drawbead height lead to significant changes for the material properties. A variation of the drawing velocity in the observed range does not show significant effects.
CRIS-Team WoS Importer:2019-07-12

Surface modification of additively manufactured parts by forming - Hafenecker, Jan; Kuball, Clara-Maria; Rothfelder, Richard; Schmidt, Michael; Merklein, Marion (ESAFORM 2021, 2021)
Additive manufacturing (AM) has many advantages compared to conventional processes. Of particular interest is the tool-less manufacturing of components, which allows one component to differ from the next completely and has the possibility of producing complex geometries. At the same time, however, AM has deficits such as long production times, low production tolerances and low surface qualities compared to conventional processes. Therefore, a finishing process using machining is often necessary, which extends the manufacturing time and produces waste. Thus, the avoidance of machining rework is of high interest, especially with expensive materials such as stainless steel or titanium. One approach to avoid machining processes is to use forming technology. By applying a forming operation, surfaces can be smoothened and geometrical aspects can be defined more sharply. Especially for functional surfaces, this procedure is favorable because of the work hardening, which in turn increases the strength of the material. Using the example of laser-based powder bed fusion (PBF-LB) followed by a cup backward extrusion process, two materials, which are frequently used in AM are investigated. On the one hand, the titanium alloy Ti-6Al-4V, as a material with low machinability and low formability at room temperature, and the stainless steel 316 L. Compared to Ti-6Al-4V, 316 L has a higher formability. Cylinders are built using PBF-LB and then formed to smoothen the surface and achieve a higher geometrical accuracy concerning edges. Formed, additively made parts have a more defined geometry, namely sharp edges and a surface roughness reduced by up to 90 %
Keywords: Additive Manufacturing; Forming; Surface Modification

Surface modifications for adaption of tribological conditions in sheet-bulk metal forming processes - Löffler, Maria; Andreas, Kolja; Engel, Ulf; Weikert, Tim; Tremmel, Stephan; Wartzack, Sandro; Stangier, Dominic; Tillmann, Wolfgang; Merklein, Marion (Proceedings THE "A" Coatings, 2016)
Keywords: Sheet-bulk metal forming; Coatings; Friction

Surface structuring of forming tool surfaces by high feed milling - Freiburg, D.; Löffler, Maria; Merklein, Marion; Biermann, D. (2017)
LFT Import::2019-08-05 (2255)

Systematic exploration of the L-PBF processing behavior and resulting properties of β-stabilized Ti-alloys prepared by in-situ alloy formation - Huber, Florian; Papke, Thomas; Kauffmann, Constantin; Rothfelder, Richard; Krakhmalev, Pavel; Merklein, Marion; Schmidt, Michael (Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing, 2021)

Tailored heat treated accumulative roll bonded aluminum blanks: failure under bending stresses - Nguyen, H.; Boehm, W.; Tsoupis, Ioannis; Göken, Mathias; Höppel, Heinz Werner; Schmidt, Christian; Hausöl, Tina; Ruppert, Mathis; Merklein, Marion (Production Engineering, 2016)
Ultrafine-grained accumulative roll bonded (ARB) sheet metals of aluminum alloys have a high potential for lightweight construction. The mechanical properties can be enhanced regarding strength and ductility by the combination of ARB and a local heat treatment according to the Tailor Heat Treated Blanks technology. The present investigation focuses on the failure behavior of ultrafine-grained ARB blanks. Due to the low formability of these high-strength ARB metals, a detailed understanding of the failure mechanisms is essential. For this purpose, an established approach to determine the different stages of damage of the material for conventional materials is now applied to multilayered aluminum in the as-received and heat-treated condition. In this context, air bending tests are used to qualify and quantify the bending and forming behavior of ARB sheets of AA1050A and AA6016 aluminum alloys.
Keywords: Tailor Heat Treated Blanks (THTB); Ultrafine-grained microstructure (UFG); Failure; Formability; Bending; Accumulative roll bonding (ARB)

Tailored heat treated accumulative roll bonded aluminum blanks: Microstructure and mechanical behavior - Maier, Verena; Hausöl, Tina; Schmidt, Christian; Böhm, Wolfgang; Hung Nguyen,; Merklein, Marion; Höppel, Heinz Werner; Göken, Mathias (Metallurgical and Materials Transactions A-Physical Metallurgy and Materials Science, 2012)
Aluminum alloy AA6016 was accumulative roll bonded up to eight cycles and investigated regarding formability by bending tests. Due to the limited bendability of accumulative roll bonding (ARB) processed materials, a tailored laser heat treatment was performed along the bending edge before forming. This tailored laser heat treatment causes a local recrystallization and recovery of the bending samples at the deformation zone, which locally increases ductility and allows higher bending angles achievable with lower forming forces. Between the recrystallized heat treated zone and the unaffected ultrafine-grained (UFG) base material, a gradient in grain size with a bimodal region is formed. This observed microstructural profile is confirmed by local mechanical testing measuring the hardness and strain rate sensitivity by nanoindentation techniques.
WW1::947

Tailored Heat Treated Blanks applied on car body parts under quasi-series conditions - Merklein, Marion; Staud, Detlev; Vogt, Uwe (International Journal of Microstructure and Materials Properties, 2008)
LFT Import::2019-07-29 (1507)

Tailored Heat Treated Profiles - Enhancement of the Forming Limit of Aluminum Profiles under Bending Load - Merklein, Marion; Lechner, Michael; Schneider, Thomas; Plettke, Raoul (Key Engineering Materials, 2012)
Aluminum profiles are well-established components in lightweight constructions. However, these profiles have a small forming capability in comparison to steel profiles, which leads to a limitation in their application. Within this paper a new and innovative approach for the enhancement of the forming limit of aluminum profiles under bending load called Tailored Heat Treated Profiles (THTP) is presented. With THTP the mechanical properties of the material are locally modified by a short-term heat treatment. By this local modification the material flow during the following cold bending operation can be influenced. For the design of the heat treatment layout, the correlation between the heat treatment parameters and the material properties has to be investigated. Tensile specimens were cut out of the profile and were subsequently completely heat treated with a laser. The changes of the mechanical properties caused by the heat treatment were analyzed by tensile tests. However, with a complete softening of the profile, the formability could not be improved. To increase the formability a local heat treatment, which leads to partial softening of the profile, has to be investigated. In order to characterize the heat-affected zone (HAZ) of the laser treatment, thermal camera and microhardness measurements were carried out. Appropriate heat treatment layouts have to be found to enhance the forming limit. Different layout strategies were developed and afterwards validated by the heat treatment and forming of profiles. This paper will present the findings of this investigation and show that THTP can be used to improve the formability of aluminum profiles for bending operations. © (2012) Trans Tech Publications.
LFT Import::2019-07-29 (1801)
Keywords: Aluminum profiles; Bending; Enhancement of formability; Tailored heat treatment

Tailored Heat Treatment Strategy for the Orbital Forming of Functional Components from EN AW-7075 - Hetzel, Andreas; Biburger, Michael; Lechner, Michael; Merklein, Marion (Springer, 2024)
The application of forming operations instead of conventional cutting processes is a practical approach to increase material efficiency and functional integration, thus addressing lightweight design. In this context, the innovative process class of Sheet-Bulk Metal Forming is presented, which combines the advantage of bulk and sheet metal forming. One of the assigned processes for the manufacturing of functional components with different form elements is orbital forming. Within previous investigations, the major challenge could be identified as a control of the material flow. Since process parameters, like an increased forming force, are not sufficient to avoid process failures in form of wrinkles, other measures have to be taken into account. Especially when applying precipitation hardenable aluminum alloys, one possibility is the application of a local short-term heat treatment. By locally reversing the hardening effect of the precipitation clusters, the interaction between softened and still hard areas can be used to attain the desired material flow. Although this procedure is established for conventional sheet metal forming processes and was furthermore investigated for the orbital forming of components from the aluminum alloy EN AW-6016, the influence on the forming of high-strength aluminum from the 7xxx-series is still content of current research. Especially due to a reduced formability at room temperature, this alloy is predominantly formed at elevated temperatures. By introducing the established method of a local short-term heat treatment on 7xxx alloys, a contribution towards a possible forming at room temperature is made. Therefore, this work focuses on the development of a tailored heat treatment strategy to control the material flow during orbital forming. Specimens out of the high-strength aluminum alloy EN AW-7075 with a thickness of 2.0 mm in condition T6 are heat-treated and consequently cold formed. The results are quantified by a geometry-based analysis. The resulting strain distribution is used to verify the material flow proportions.<br
Keywords: Aluminum alloy; Local short-term heat treatment; Orbital forming

Tailored modifications of amorphous carbon based coatings for dry deep drawing - Merklein, Marion; Schmidt, Michael; Tremmel, Stephan; Andreas, Kolja; Häfner, Tom; Zhao, Rong; Steiner, Jennifer (Dry Metal Forming Open Access Journal, 2016)
Avoiding negative effects of conventional lubrication in forming operations stimulates research on lubricant-free sheet metal forming. Without lubricants, the direct contact between tool and workpiece leads to intensive interaction in terms of increasing friction and wear. Especially, when forming aluminum alloys, adhesion is detected as main wear mechanism propagating already at the initial contact between tool steel and sheet material. Thus, surface modifications need to be developed to substitute the functions of conventional lubricants. Former studies revealed that amorphous carbon based coatings improved the tribological conditions. Depending on the specific coating type adhesion and friction could be significantly reduced. Besides achieving a lower level of friction, a control of material flow is necessary to improve the forming results in deep drawing processes. Thus, there is a need for contact zones with higher and lower friction to locally accelerate or restrict the flow of the sheet material. In order to achieve these tailored tribological conditions a broad range of surface modifications needs to be developed and evaluated in a process-like environment. The tribological behavior is affected by coating properties and structure. By varying gas flow and ratio for a-C:H coatings the relationship between deposition parameters and coating properties are investigated. A further approach to realize a broader range of friction coefficients is the laser based texturing of coated tools. Additionally, a laser based heat treatment is investigated to control the sp2/sp3 ratio of ta-C coatings to affect friction and wear mechanisms. The tribological behavior of the investigated surface modifications is analyzed in ring-on-disc and flat strip drawing tests. A surface characterization is performed to identify about the wear mechanisms. Based on the modifications of a-C:H and ta-C coatings a correlation between chemical and mechanical properties and the tribological behavior in contact with zinc-coated deep drawing steel and aluminum alloys is found.
Keywords: Dry Deep Drawing; Tribology; Carbon Based Coatings; Laser Based Modification

Tailored solutions in mechanical engineering - Merklein, Marion; Lechner, Michael (Public Service Review, 2012)
LFT Import::2019-07-29 (1829)

Tailored Surfaces in Sheet-Bulk Metal Forming - Vierzigmann, Ulrich; Merklein, Marion; Engel, Ulf (Proc. 4th International Conference on Tribology in Manufacturing Processes (ICTMP), 2010)
LFT Import::2019-08-05 (288)

Tailored tempering – FE-Simulation of manufacturing components with local adjusted mechanical properties - Svec, Thomas; Merklein, Marion (Steel Research International, 2012)
LFT Import::2019-07-29 (1797)

Tailoring material properties in forming technology by a local heat treatment - Merklein, Marion; Graser, Matthias; Degner, Julia; Lechner, Michael; Herrmann, Jürgen (Advanced Metal Forming Processes in Automotive Industry, 2016)
LFT Import::2019-08-05 (2177)

Tailoring Material Properties of Aluminum by Local Laser Heat Treatment - Merklein, Marion; Böhm, Wolfgang; Lechner, Michael (Physics Procedia, 2012)
The local laser heat treatment of precipitation hardenable aluminum alloys enables the tailoring of the materials properties and the manufacturing of lightweight and crash-proof components for the body in white. For conventional aluminum sheet metals and profiles the formability is enhanced by an indirect approach. Thereby specific parts of the products are softened in order to improve the material flow towards crack critical areas during the forming operation. For innovative high-strength aluminum sheet metal with nanocrystalline grain structure produced in the Accumulative Roll Bonding process in addition to the indirect approach a direct enhancement of the formability by recrystallization effects is possible.
EAM Import::2019-03-12

Tailor-Made Forging Tools by Laser Metal Deposition - Junker, Daniel; Hentschel, Oliver; Schmidt, Michael; Merklein, Marion (Key Engineering Materials(2015), 2015)
The desire for individualized products forces the companies to a great diversity of combinable parts. This way, the clients can compile their personalized product. As this trend is not just limited on visual parts but also for functional components, laser additive manufacturing of metals is used more and more often in manufacturing. To bring more additive manufacturing into mass production, Laser Beam Melting and Laser Metal Deposition will be qualified for the use in tool manufacturing within the Bavarian research association "ForNextGen - Next Generation Tools". The first subproject within this research association investigates the potential of Laser Metal Deposition in the production of hot and cold forging tools. Within initial tests optimized process, parameters for the processing of the hot-work steel 1.2709 are determined by single welding beads. The achieved density and the inner structure are analyzed within cubes that were built with the investigated parameters. As forging tools are usually made of high-carbon tool steel, the processing of materials with a rising percentage of carbon will be part of further investigations.
LFT Import::2019-08-05 (2111)
Keywords: Additive manufacturing; Forging tool; Graded structures; Highcarbon steel welding; Tool manufacturing

Tailor Quenched Blanks - Merklein, Marion; Lechner, Michael; Kuppert, Andreas (Danish-German Aerospace Collaboration Kick-Off, 2013)
LFT Import::2019-07-29 (1944)

Targeted influencing of the mission-relevant component properties of cold-forged gearwheels - Rohrmoser, Andreas; Kiener, Christoph; Schubert, Dominik; Hagenah, Hinnerk; Drummer, Dietmar; Merklein, Marion (Konstruktion, 2019)
Cold forging offers the potential to produce ready-to-use gears in a process suitable for series production. In material pairing with a plastic gearwheel, the component properties of the steel gearwheel have a decisive effect on the wear behaviour and service life of the pairing. This results in requirements for the component properties that must be taken into account when designing the cold forging process. In the context of this article, the improvement of the resulting running-in behaviour of a steel-polyamide gear pairing by targeted measures within the design of the cold forging process of the steel pinion is investigated.
CRIS-Team Scopus Importer:2021-04-20

Teilprojekt 4: Berücksichtigung funktionsrelevanter Gestaltabweichungen bei der Auslegung von Umformprozessen zur Herstellung von Stirnrädern mit Sonderverzahnung durch Fließpressen - Rohrmoser, Andreas; Hagenah, Hinnerk; Merklein, Marion (Abschlussbericht DFG-Forschungsgruppe FOR 2271, 2. Phase.Prozessorientiertes Toleranzmanagement mit virtuellen Absicherungsmethoden, 2023)

Temporal and spatial detection of the onset of local necking and assessment of its growth behavior - Jaremenko, Christian; Affronti, Emanuela; Merklein, Marion; Maier, Andreas (Materials, 2020)
This study proposes a method for the temporal and spatial determination of the onset of local necking determined by means of a Nakajima test set-up for a DC04 deep drawing and a DP800 dual-phase steel, as well as an AA6014 aluminum alloy. Furthermore, the focus lies on the observation of the progress of the necking area and its transformation throughout the remainder of the forming process. The strain behavior is learned by a machine learning approach on the basis of the images when the process is close to material failure. These learned failure characteristics are transferred to new forming sequences, so that critical areas indicating material failure can be identified at an early stage, and consequently enable the determination of the beginning of necking and the analysis of the necking area. This improves understanding of the necking behavior and facilitates the determination of the evaluation area for strain paths. The growth behavior and traceability of the necking area is objectified by the proposed weakly supervised machine learning approach, thereby rendering a heuristic-based determination unnecessary. Furthermore, a simultaneous evaluation on image and pixel scale is provided that enables a distinct selection of the failure quantile of the probabilistic forming limit curve.
CRIS-Team Scopus Importer:2020-07-17
Keywords: Artificial intelligence; Classification; Deep learning; Forming limit curve; Machine learning; Pattern recognition; Segmentation; Sheet metal forming

Test method for friction characterization of rivets - Wituschek, Simon; Kuball, Clara-Maria; Merklein, Marion; Lechner, Michael (Defect and Diffusion Forum, 2020)
Due to continuously increasing requirements on lightweight sheet metal constructions, new processes and technologies are necessary to face current and future challenges. A trend in lightweight construction is the multi-material mix with sheets of different geometric and mechanical properties. To manufacture these so-called composite structures, new joining technologies and methods are required. One possibility is the further development of the self-pierce riveting joining process. For the simulation and evaluation of new and adapted processes of self-pierce riveting, numerical models are used to investigate process parameters and constraints. Besides precise material models for the numerical simulation of this joining process, the identification of friction parameters between the individual sheets and rivet elements is necessary to achieve exact results. Thus, a method is necessary to identify the friction coefficients between rivet elements and sheets. Such a method is presented and evaluated in this work. Different process parameters like the relative speed are varied for the experimental investigations and an analysis of the respective influence on the resulting friction coefficients is conducted. For the use of the test set-up, coefficients of friction are determined for rivet elements “RIVSET® C 5.3x5.5” (Böllhoff GmbH) coated with Almac® in combination with two different sheet materials HCT590X+Z and EN-AW 6014.
CRIS-Team Scopus Importer:2020-12-04
Keywords: Friction; Joining; Self-piercing riveting

The correlation coefficient method: from the beginning to the development - Merklein, Marion; Affronti, Emanuela; Kuppert, Andreas; Maier, Anne-Kathrin; Lechner, Michael (Workshop Time-dependent Methods for the Evaluation of FLC, 2014)
LFT Import::2019-08-05 (2053)

The influence of the annealing process in the fabrication of helical needles for the suture in deep wound cavities - Plettke, Raoul; Vipavc, Daniel; Grüner, Martin; Hagenah, Hinnerk; Merklein, Marion (International Journal of Computer Integrated Manufacturing, 2014)
The standard procedure of a surgical suture can be very difficult to perform in deep-wound cavities because the available space is not enough to perform the complicated movements required for the knot or to handle the needle. To improve this situation a new kind of hollow, helical needle was developed and filed for patent. To ensure the manufacturability of this kind of needle, a prototype and a prototypical tool were designed and tested. As a prototypical basis, commercially available cannulas were selected. Coil winding was used as a forming process to bring the cannula into the helical form. The material properties of the surgical steel and the work hardening that the semi-finished products underwent lead to challenges for the forming process. The limitations of springback and low formability reduce the possible radius of the helix. Therefore, a soft annealing of the cannula was investigated. However, in surgical needles, stiffness is of great importance. Since hardening by quenching is not possible, annealing parameters were chosen to retain the necessary stiffness. Based on the data obtained from tests of annealing parameters, four final geometries of helical needles were designed and first prototypes were manufactured. © 2013 Taylor & Francis.
LFT Import::2019-07-29 (1901)
Keywords: annealing; case study; deep wound; helical needle; suture; winding

Thermo-mechanical Laser Process Design: Virtual Reality in Use - Komlodi, Attila; Niebling, Frank; Merklein, Marion; Otto, Andreas (EuroPAM, Proceedings of the 13th European Conference and Exhibition on Digital Simulation for Virtual Prototyping, Virtual Manufacturing and Virtual Environment, 16-17. Oktober, 2003)
LFT Import::2019-08-05 (971)

Thermo-Mechanical Properties of Tailor Welded Blanks in Hot Sheet Metal Forming Processes - Lamprecht, K.; Deinzer, G.; Stich, A.; Lechler, Jürgen; Stöhr, Thomas; Merklein, Marion (Proc. 50th Conference of IDDRG 2010, 2010)
LFT Import::2019-08-05 (226)

Thermo-mechanical sheet metal forming of aero engine components in Ti-6Al-4V–PART 1: Material characterisation - Odenberger, E.-L.; Hertzman, J.; Thilderkvist, P.; Merklein, Marion; Kuppert, Andreas; Stöhr, Thomas; Lechler, Jürgen; Oldenburg, M. (International Journal of Material Forming, 2012)
LFT Import::2019-07-29 (1838)

The use of dry film lubricants in aluminium sheet metal forming - Meiler, M.; Pfestorf, Markus; Geiger, Manfred; Merklein, Marion (Wear, 2003)
LFT Import::2019-07-16 (1005)
Keywords: Aluminum; Friction; Textures; Tribology

Time dependent determination of forming limit diagrams - Merklein, Marion; Kuppert, Andreas; Geiger, Manfred (CIRP Annals - Manufacturing Technology, 2010)
LFT Import::2019-07-29 (297)
Keywords: Failure criterion; Forming; Sheet metal

Time dependent FLC determination - Comparison of different algorithms to detect the onset of unstable necking before fracture - Hotz, Walter; Merklein, Marion; Kuppert, Andreas; Friebe, Harald; Klein, Markus (Key Engineering Materials, 2013)
The ISO standard 12004-2:2008E for the determination of forming limit curves based on the section method was approved in 2008. About 4 years of measuring experience in different laboratories has shown advantages and weaknesses of the standard and is leading to some minor changes in the specification. In the years from the development of this standard until today a further technical development of the optical measuring devices occurred, so that it is now possible to determine forming limit curves using the time history of the test. This procedure of determination is referred to a time dependent technique and could be the basis of the ISO 12004 part 2 proposal worked out by the work group "Erweiterung FLC ISO 12004" of the German group of the IDDRG. This publication recapitulates existing work which was carried out from the IDDRG work group regarding the determination of forming limit curves for sheet metal materials. On one hand known issues with the current section based approach are discussed and on the other hand it deals with a comparison of different algorithms to determine the FLC from the time history of the Nakajima test using strategies to identify the instant of onset of instable necking. The different time dependent algorithms [1] utilised are automatically selecting the area where necking is leading to fracture and then analyze the time history of such points using the first or the second time derivative of the true major strain, or of the true thinning strain using methods like: correlation coefficient (modified method based on [2]), gliding correlation coefficient, linear best fit (modified method based on [3]) and gliding difference of mean to median. The resulting experimental FLC points are compared with the results from the section technique described in ISO 12004 part 2 and with the maximum strain values measured in each test. Further a large number of forming limit curves were determined and used for a comparison of these different methods to define the most promising time dependent algorithm, which was selected as a suggestion for the working group defining the new proposed ISO standard 12004 part 2. © (2013) Trans Tech Publications.
LFT Import::2019-07-29 (1927)
Keywords: Forming limit curve (FLC); Material characterization; Time depending evaluation methods

Titanium metal sheet structures of various wall thicknesses with additional functional elements prepared by selective electron beam melting in a powder bed - Juechter, V.; Schaub, Adam; Merklein, Marion; Singer R., F. (5th International Conference on Additive Technologies - iCAT2014, 2014)
LFT Import::2019-08-05 (2051)

Tool design for cold forging of high nitrogen steels - Noneder, Johannes; Engel, Ulf; Merklein, Marion (Proceedings of the 12th International Cold Forging Congress, 2011)
LFT Import::2019-08-05 (1741)

Tool development based on modelling and simulation of hot sheet metal forming of Ti-6Al-4V titanium alloy - Odenberger, E. -L.; Oldenburg, M.; Thilderkvist, P.; Stöhr, Thomas; Lechler, Jürgen; Merklein, Marion (Journal of Materials Processing Technology, 2011)
In the aero engine industry alternative manufacturing processes for load carrying aero engine structures imply fabrication. The concept of fabrication involves simple forgings, sheet metals and small ingots of e.g. titanium alloys which are welded together and heat treated. In the concept phase of the product development process, accurate evaluations of candidate manufacturing processes with short lead times are crucial. In the design of sheet metal forming processes, the manual die try out of deep drawing tools is traditionally a time consuming, expensive and inexact process. The present work investigates the possibility to design hot forming tools, with acceptable accuracy at short lead times and with minimal need for the costly die try out, using finite element (FE) analyses of hot sheet metal forming in the titanium alloy Ti-6Al-4V. A rather straightforward and inexpensive approach of material modelling and methods for material characterisation are chosen, suitable for early evaluations in the concept phase. Numerical predictions of punch force, draw-in and shape deviation are compared with data from separate forming experiments performed at moderately elevated temperatures. The computed responses show promising agreement with experimental measurements and the predicted shape deviation is within the sheet thickness when applying an anisotropic yield criterion. Solutions for the hot forming tool concept regarding heating and regulation, insulation, blank holding and tool material selection are evaluated within the present work. © 2011 Elsevier B.V. All rights reserved.
LFT Import::2019-07-29 (1690)
Keywords: FEM simulation; Hot forming test; Hot sheet metal forming; Ti-6Al-4V; Titanium alloys; Validation

Tool Load Sensitivity against Multidimensional Process Influences in Microblanking of Thin Metal Foils with Silicon Punches - Hildering, Sven; Michalski, Markus; Engel, Ulf; Merklein, Marion (Journal of Manufacturing Science and Engineering, 2016)
LFT Import::2019-07-29 (2169)

Tool Sided Surface Modifications in the Industrial Environment - Wild, Thomas; Merklein, Marion (Lecture Notes in Production Engineering (LNPE), 2020)
In order to meet the increasing requirements on modern production, the innovative process class of sheet-bulk metal forming has proved to be suitable. Particularly lightweight construction and functional integration lead to complex shaped functional elements. In addition to this, the widespread use of high-strength materials also results in challenges in the production of such components by forming. This leads to demanding forming processes, in which the die filling is often insufficient due to unintended material flow. In this respect, tailored surfaces offer one possibility of controlling the material flow and thus increasing component quality. This concept refers to the local adaptation of the tribological system during the forming of the components. Within this research project it is the objective to transfer the process knowledge that has been generated in the Transregional Collaborative Research Centre 73 (TCRC73) to the industrial environment. This involves investigating the impact of the requirements and influences of mass production on the efficacy and service life of the tailored surface. For this purpose, based on a finely ground reference surface, the effects of abrasive blasting and laser beam polishing as surface modifications of tool steels are investigated in a laboratory and industrial scale. Emphasis is placed on the formation of the modified surfaces, the effects on the tribological operational behaviour and the impact on the fatigue behaviour of tool steels.<br

Tool System for Ultrasonic-Assisted Forming and Material Characterisation with 15 kHz Oscillation Frequency - Michalski, Markus; Leicht, Uwe; Engler, S.; Merklein, Marion (Applied Mechanics and Materials, 2015)
LFT Import::2019-07-29 (2102)

Towards an holistic account on residual stresses in full-forward extruded rods: Experiment, modeling and simulation of forming and operation phases - Floros, Dimosthenis; Jobst, Andreas; Kergaßner, Andreas; Merklein, Marion; Steinmann, Paul (Archive of Applied Mechanics, 2021)
An holistic view is attempted towards prediction of the effect of residual stresses induced by full-forward extrusion on fatigue life of workpieces during operation. To study the effect of constitutive model on the accuracy of forming simulations, a combined nonlinear isotropic/kinematic hardening model as well as the isotropic hardening part of the same model are calibrated based on five compression-tension-compression uniaxial stress experiments. A full-forward extrusion finite element model is developed adapting both the aforementioned hardening plasticity models and the predicted residual stress states at the surface of the workpiece are compared against that of a corresponding forming experiment. Results show residual stress predictions of remarkable accuracy by the FE-models with the isotropic hardening model. The effect of residual stresses on fatigue life of the workpiece is qualitatively studied by uncoupled multiscale simulations featuring gradient crystal plasticity at the microscale. While the effective (homogenized) macroscale response indicates elastic response during a macroscopically cyclic loading, plasticity accompanying reduction of residual stresses is still present at the microscale within, e.g. grain boundaries.
CRIS-Team Scopus Importer:2021-03-19
Keywords: Cold forming; FE-simulations; Kinematic hardening; Multiscale modeling; Residual stress

Towards virtual deformation dilatometry for the design of hot stamping process - Bambach, Markus; Buhl, Johannes; Hart-Rawung, T.; Lechner, Michael; Merklein, Marion (Procedia Engineering, 2017)
Hot stamping is a well-established process for the production of structural automotive parts with an excellent strength-to-weight ratio. The complexity of the thermo-mechanical history in hot stamping requires a precise virtual design of hot stamping processes. The thermal and mechanical characteristics of the most common press hardening steel 22MnB5 were investigated comprehensively and are well represented by numerical models. For new steel compositions and parts involving tailored tempering, numerous experiments, e.g., on a deformation dilatometer or thermo-mechanical simulator are needed to characterise the microstructure evolution and the resulting properties. If appropriate material models were available, new steel compositions and thermo-mechanical histories could be partly explored virtually by simulated deformation dilatometer tests. This paper presents a comparison of experimental and virtual deformation dilatometer tests for the hot stamping steel 22MnB5. The virtual dilatometer is implemented as finite element model in the software LS-Dyna based on the material model∗MAT248. With this model, virtual and real dilatometer curves correspond well only for conditions of full martensitic hardening, while pre-strains cause larger differences between model and experiments. When the most sensitive model parameters are formulated as a function of pre-strain, all experimental dilatometer curves can be reproduced by the model. Such a data-driven extension of the model seems to be effective for creating a virtual dilatometer model of high accuracy.
CRIS-Team Scopus Importer:2023-03-29
Keywords: Autenite decomposition model; Dilatometry test; Hot Stamping

Tranciatura ad alta precisione di fogli di rame mediante punzoni in silicio monocristallino rivestiti e non - Hildering, Sven; Becsi, L.; Merklein, Marion; Mescheder, U. (Lamiera, 2012)
LFT Import::2019-07-29 (1808)

Transformation kinetics of the hot stamping steel 22MnB5 in dependency of the applied deformation on the austenitic microstructure - Merklein, Marion; Svec, Thomas (Proc. 50th Conference of IDDRG 2010, 2010)
LFT Import::2019-08-05 (277)

Trends in der Aluminiumumformung - Merklein, Marion; Lechner, Michael; Kuppert, Andreas (Tagungsband zum Cluster-Forum Innovationen in der Aluminium-Umformtechnik, 2012)
LFT Import::2019-07-29 (1943)

Triangulation based digitizing of tooling and sheet metal part surfaces? measuring technique, analysis of deviation to CAD and remarks on use of 3D-coordinate fields for the finite element analysis - Hecht, Joachim; Lamprecht, Klaus; Merklein, Marion; Galanulis, K.; Steinbeck, J. (Proceedings of the 12th International Conference on Sheet Metal (SheMet), 01.-04.04., Palermo, Italy, 2007)
The dynamic development of highly accurate optical measuring machines within the last years pushed the introduction of digitizing techniques to many applications in the fields of quality control, reverse engineering and rapid prototyping. By projecting fringe patterns onto the object's surface and recording pictures of the curvature dependant deformation of the pattern, 3D coordinates for each camera pixel are calculated on the basis of the principle of triangulation. The generation of a polygon mesh can be used for the analysis of the deviation of a die or a formed part to the initial CAD data, i.e. by means of full field or section based comparison. This paper presents the application of the above mentioned techniques on a double sheet hydroforming process. The gathered 3D data of the clam-shell part as well as of the tooling dies served for the calculation of the deviation to the respective reference geometry. With respect to the utilization of digitized tooling data within the finite element analysis, further investigations were performed on the impact of data reduction strategies. Aiming on the minimization of the necessary number of elements, representing the tooling surface in a discrete state, and on the request for a sufficient degree of accuracy, these strategies have to be considered of high priority.
LFT Import::2019-08-05 (1383)
Keywords: FE simulation; Sheet metal forming and tooling; Triangulation based digitizing

Tribiological Properties of Dry Film Lubricants in Aluminium Sheet Metal Forming. - Meiler, M.; Pfestorf, Markus; Merklein, Marion; Geiger, Manfred (Processing of the 2nd International conference on Tribology in Manufacturing Processes, Nyborg, Denmark, June 15-18 2004, 2004)
LFT Import::2019-08-05 (1057)

Tribological and thermal behavior of laser implanted tool surfaces for hot stamping AlSi coated 22MnB5 sheets - Schirdewahn, Stephan; Spranger, Felix; Hilgenberg, Kai; Merklein, Marion (Defect and Diffusion Forum, 2022)
In the automotive industry, the development of electrically powered vehicles has become a major forward-looking topic. For improving the range and thus the efficiency of electric cars, lightweight construction has gained even more importance. In this regard, hot stamping has been established as a suitable and resource efficient process to manufacture high-strength and lightweight body-in-white components. This method combines hot forming and quenching of boron-manganese steel 22MnB5 in a single process step. As a result, complex structures with thin sheet thicknesses and high ultimate tensile strength up to 1500 MPa are generated. However, the use of lubricants is not possible at elevated temperatures, which subsequently leads to high thermo-mechanical tool stresses. As a side effect, high friction and severe wear occur during the forming process, which affect the resulting part quality and maximum tool life. Therefore, the aim of this study is to improve the tribological performance of hot stamping tools by using a laser implantation process. This technique is based on manufacturing highly wear resistant, separated and elevated structures in micrometer range by embedding hard ceramic particles into the tool material via pulsed laser radiation. As a result, highly stressed areas on the tool surface can be modified locally, which in turn influence the tribological and thermal behavior during the forming process. In this regard, laser implanted and conventionally tool surfaces were investigated under hot stamping conditions. A modified pin-on-disk test was used to analyze the friction coefficient and occuring wear mechanisms. Furthermore, quenching tests as well as hardness measurements were carried out to gain in-depth knowledge about the cooling behavior of the modified tool surfaces and its impact to the resulting mechanical part properties.<br
Keywords: Hot stamping; Laser implantation; Surface structuring; Tribology

Tribological and thermal investigation of modified hot stamping tools - Neubauer, Franziska; Merklein, Marion (Tribology in Industry, 2019)
Direct hot stamping is an established manufacturing process to produce safety-relevant car body components, while t-he hot blank is formed and quenched simultaneously in a water cooled press. In order to protect the semi-finished parts against oxidation the surfaces are coated with aluminum silicon. As a side effect this coating system leads to adhesive wear on the tool surface, which reduces the tool life. Due to the high temperatures it is not possible to use lubricants as wear protection. For this reason a suitable surface modification for hot stamping tools is required to increase the wear resistance. In the scope of this study the tribological behavior of different modificatiosn is investigated. The main purpose of these wear protective layers is to decrease the adhesive wear on the tool surface. The wear characterization is carried out with a modified pin-on-disc test. During the experiments the pin is guided over the blank with a robot system. In addition, the contact area is cooled after each wear track to simulate the thermal alternating stresses of the hot stamping process. For the evaluation of the wear behavior a new developed analysis method is used, which enables the calculation of the adhesive and abrasive wear volume.
CRIS-Team Scopus Importer:2019-06-21
Keywords: Alloying; Coatings; Hot stamping; Wear

Tribological aspects in manufacturing processes of microstructured components and their tribological behavior in operation - Schrader, Tobias; Weschta, Martin; Merklein, Marion; Tremmel, Stephan; Engel, Ulf; Wartzack, Sandro (Proc. 6th International Conference on Tribology in Manufacturing Processes and Joining by Plastic Deformation, 2014)
An ever increasing mobility and a shortage of resources lead to restrictive politically driven limits for fuel consumption as well as an increasing demand of customers for efficient vehicles. Though electrification of cars proceeds, combustion engines will play an important role for conventional and hybrid concepts within next decades. Thus, for a contribution to increasing energy efficiency of vehicles it is vital to trace sources of friction losses and to identify possibilities for friction reduction in combustion engines. Therefore, the follower as a main contributor to friction losses in valve trains was chosen as a demonstrator for friction reduction effects by microstructured components. However, the realization of theoretically advantageous microstructures with filigree geometries is challenging for manufacturing technologies. The present study focuses on the elaboration of a technological basis for a repeatable production of components with microstructured surfaces by a combined cup backward extrusion micro coining process, coping with the demands of large-lot production. For realization of a high accuracy the influence of friction on geometry of microstructured components was investigated. In addition, running-in of components is decisive for final geometry and tribological behavior of microstructured surfaces and hence considered as well.
Keywords: Accuracy; Microstructures; Tribology

Tribological Behavior of Carbon Based Coatings Adapted to Lubricant-Free Forming Conditions - Tenner, Jennifer; Zhao, Rong; Tremmel, Stephan; Häfner, Tom; Schmidt, Michael; Merklein, Marion (International Journal of Precision Engineering and Manufacturing - Green Technology, 2018)
In conventional deep drawing lubricants are applied to achieve low friction and wear. However, most lubricants contain environmental harmful ingredients. Global trends like sustainability and efficient resource usage motivate the development of lubricant-free deep drawing. However, dry contact conditions lead to intensive interaction between tool and workpiece especially for aluminum alloys with high adhesion tendency towards tool steel. First investigations revealed promising results for diamond like carbon (DLC) coated tools in lubricant-free tests. Therefore, in this study the lubricant-free friction and wear behavior of DLC coatings is investigated in strip drawing tests. To ensure industrial-like conditions commonly used deep drawing steel with zinc coating and an aluminum alloy were selected as sheet material. The properties of DLC coatings were modified at different scales to attain tailored tribological conditions. A laser based heat treatment achieved an increase of sp2 hybridization and thus leads to increased friction. Different mechanical pre- and post-treatment strategies like polishing and brushing proved that a smooth tool surface is beneficial for the tribological conditions in dry contacts. With laser generated structures a modification of friction was realized with varying degree of coverage for DC04. In contact with AA5182 the application of structures is limited due to adhesion.
CRIS-Team Scopus Importer:2022-06-05
Keywords: Carbon based coatings; Dry deep drawing; Surface modification; Tribology

Tribological Behavior of Different Tool Steels and Surface Properties under Hot Stamping Conditions - Schwingenschlögl, Patrik; Tenner, Jennifer; Merklein, Marion (Key Engineering Material, 767, 2018)
LFT Import::2019-08-05 (2313)
Keywords: 22MnB5; Friction; Hot stamping; Tool steel; Wear

Tribological Behavior of High-Strength Aluminum Alloys in Combination with Dry Lubricants at High Forming Temperatures - Rigas, Nikolaos; Junker, Friedhelm; Berendt, Erik; Merklein, Marion (Defect and Diffusion Forum, 2022)
High-strength aluminum alloys provide great potential for weight reduction in vehicle and aircraft production. Nevertheless, forming of these materials is limited at room temperature. Thermally supported forming operations such as hot forming and quenching (HFQ®) allow forming of components without failure and reduced springback. Currently, the adhesive wear and high friction limit the use of HFQ®-operations for high-strength aluminum alloys. Out of this reason, the present paper describes the tribological performance of new developed dry lubricants at elevated temperatures for the alloy AA7075. For this purpose, strip drawing tests were carried out in a modified open tribological system at temperatures between 20 °C and 400 °C. Additionally, the melting behavior of these lubricants, as well as the variation of the lubricant thickness, were investigated. The results show a reduction of the coefficient of friction at elevated temperatures.
Keywords: Tribology; Hot stamping; Lubrication; High-strength aluminum

Tribological behavior of Zn coated 22MnB5 in hot stamping - Schwingenschlögl, Patrik; Tenner, Jennifer; Andreas, Kolja; Merklein, Marion (Steels in Cars and Trucks, 2017)
LFT Import::2019-08-05 (2235)

Tribological challenges in press hardening - Schwingenschlögl, Patrik; Merklein, Marion (Stahl und Eisen, 2019)
Hot stamping has established as a common technology for manufacturing safety-relevant components in modern vehicle bodies. By applying thin sheet thicknesses, using hot stamped parts offers the chance of improving crash performance while towering the mileage. The most commonly used material for hot stamped components is the high-strength-steel 22MnB5. In order to avoid the formation of oxide scale during the heat treatment and the subsequent forming process, an AISi coating is applied to the boron-manganese-steel. Due to the forming temperatures between 600 °C and 850 °C, no suitable lubricants have been found yet. Thus, high friction and severe wear occur during the forming. This has an impact on the resulting part quality as well as the tool lifetime. As a consequence, future measures that reduce the tribological loads have to be found in order to improve the robustness and the efficiency of industrial hot stamping applications. Within this study, friction and wear are characterized for different workpiece and tool temperatures, relative velocities and contact pressures. Based on the experimental results, suggestions regarding the process design of hot stamping applications will be given.
CRIS-Team Scopus Importer:2021-04-20

Tribological characterization of PVD-coatings - Schrader, Tobias; Engel, Ulf; Merklein, Marion (Key Engineering Materials, 2010)
LFT Import::2019-07-29 (1015)
Keywords: Coating; Cold forging; Wear

Tribological Conditions in Sheet-Bulk Metal Forming - Vierzigmann, Ulrich; Merklein, Marion; Engel, Ulf (2nd International Conference of Engineering Against Fracture, 2011)
LFT Import::2019-08-05 (1739)

Tribological conditions within hot stamping process - Merklein, Marion; Wieland, Michael; Zöller, Fabian (Proc. of 7th Forming Technology Forum - Warm and Hot Forming, 2014)
LFT Import::2019-08-05 (2043)

Tribological Investigations on Coated Steel Sheets using the Dry Film Lubricant Drylube E1 - Tolazzi, Massimo; Merklein, Marion; Meiler, M. (Sheet Metal 2005, Proceedings of the 11th International Conference on Sheet Metal; Advanced Materials Research, 2005)
Tribological aspects strongly influence the deep drawing behaviour of sheet metal, being responsible for both the punch force and the material draw-in from the flange. Recent developments in lubrication technology have shown that dry film lubricants can be a good alternative to conventional fluid lubricants in case of aluminium sheets. Their main advantages are the homogeneous distribution on the blank surface, the good adhesion to the surface and the possibility of applying it already in the rolling mill. In order to introduce this technology in series production also for steel sheets more knowledge concerning the influence of the lubricant amount on the drawing forces is needed. A further important aspect to be considered is the surface quality of the steel grades and its interactions with the dry lubricant. In this paper four steel grades with different mechanical and/or surface properties are considered. After a microscopical and topographical investigation of the surface the materials were tested in a cup drawing test after applying two different amounts of the dry film lubricant Drylube El. Further process parameters which were varied are the blank holder force FN and the drawing ration β. In this way, information about the influence of the lubricant amount on both the drawing force and on the maximum blank holder force Fz could be obtained for three different values of β. The experimental results have shown how a strong decrease of the lubricant amount (from 1.0 down to 0.5 g/m2) causes, at a given drawing ratio, only a small increase in the maximum drawing force as well as a small increase in the maximum blank holder force.
LFT Import::2019-08-05 (1129)
Keywords: Dry film lubricant; Sheet metal; Tribotogy

Tribological measures for controlling material flow in sheet-bulk metal forming - Löffler, Maria; Andreas, Kolja; Engel, Ulf; Schulte, Robert Karl; Gröbel, Daniel; Krebs, Eugen; Freiburg, Dennis; Biermann, Dirk; Stangier, Dominic; Tillmann, Wolfgang; Weikert, Tim; Wartzack, Sandro; et al. (Production Engineering, 2016)
Sheet-bulk metal forming (SBMF) is characterized by successive and/or simultaneous occurrence of quite different load conditions regarding stress and strain states. These conditions significantly influence the material flow and thus the geometrical accuracy of the components. To improve the product quality a control of the material flow is required. An appropriate approach is given by locally adapted tribological conditions due to surface modifications of tool and workpiece, so-called tailored surfaces. Within the present study different methods to adapt the surfaces are presented and investigated with respect to their tribological effectiveness in SBMF. In a first step, requirements regarding necessary adaptions of the friction values for two SBMF processes are numerically defined. Based on the requirements different tailored surfaces are presented and analyzed regarding their tribological influence. Finally, the potential of surface modifications to improve SBMF processes is shown.
Keywords: Tribology; Surface modification; Sheet-bulk metal forming

Tribological performance of localized dispersed X38CrMoV5-3 surfaces for hot stamping of Al-Si coated 22MnB5 sheets - Schirdewahn, Stephan; Spranger, Felix; Hilgenberg, Kai; Merklein, Marion (Hot Sheet Metal Forming of High-Performance Steel CHS², 2019)
Over the last years, the weight of modern car bodies has risen significantly due to the increasing customers’ demand for comfort and safety equipment. However, this ongoing trend leads to an increasing fuel consumption and thus to higher carbon dioxide emissions. In order to counteract these problems, hot stamping has been established in the automotive industry as a key technology for lightweight construction, regarding the manufacturing of safety-relevant car body components. Hot stamped parts are commonly made out of boron-manganese steel 22MnB5, which is initially austenized and subsequently formed and quenched in one process step. As a result, geometrical complex structures with an ultimate tensile strength of 1500 MPa are generated. The surfaces of the workpieces are coated with an Al-Si layer to avoid oxide scale formation and to ensure corrosion protection. However, the coating system leads to an increased adhesive wear on the tool surface due to the high thermo-mechanical tool stresses. Therefore, a time and cost consuming rework of the hot stamping tools is required. The aim of this study is to increase the tribological performance of hot stamping tools by using a laser implantation process. This technique allows the manufacturing of separated, elevated and dome-shaped microstructures on the tool surface in consequence of a localized dispersing of hard ceramic particles by pulsed laser radiation. The generated surface features offer great potential for reducing the tribological load, due to their high hardness and wear resistance. For this purpose, the friction coefficient of unmodified and laser implanted tool surfaces were examined and compared by using a modified pin-on-disk test. In addition, the surfaces were analyzed by optical measurements in order to quantify the amount of wear.<br

Tribology and influence of tool coatings on frictional conditions within forming of advanced high strength steels - Merklein, Marion; Geiger, Manfred; Kaupper, Markus (Conference Proceedings, 7th International Conference THE Coatings, 2008)
LFT Import::2019-08-05 (205)

Überblick der Blechmassivumformung - Merklein, Marion; Opel, Simon; Schneider, Thomas; Koch, Johannes Peter Karl (Umformtechnik, 2012)
LFT Import::2019-07-29 (1788)

Über die Blechprüfung von heute - Merklein, Marion; Suttner, Sebastian; Hofmann, Maren; Kuppert, Andreas (Tagungsband Werkstoffprüfung, 2012)
LFT Import::2019-08-05 (1839)

UHS Steel Formability in Flexible Roll Forming - Mäntyjärvi, Kari; Merklein, Marion; Karjalainen, Jussi A. (Proceedings of the SheMet2009, 2009)
Ultra-high-strength (UHS) steels are very interesting materials for many applications where high strength can be utilized to create lighter and more effective constructions. The poor formability of UHS steels, however, may limit the usefulness of these materials in many applications. In this work, some experiments using a flexible roll forming machine developed at the Chair of Manufacturing Technology (LFT), University of Erlangen-Nuremberg were carried out using 4mm-thick bainitic martensitic UHS steels (YS/TS 960/1000 and 1100/1250) and the outcomes have been analysed. Results of these experimental tests show that using roll forming it is possible to bend test materials to an angle of 90° without damages with an evidently smaller radius than in air bending. The radius obtained using roll forming can be as small as 40% of the value used in air bending. Tests also show that with the method used in these tests it is possible to make roll forming for the whole length of the plate. The tests proved that the NC-controlled single-step roll forming method has potential for manufacturing small batches of bend profiles; however, more development has to be carried out if the process is to be made suitable for industry. © (2009) Trans Tech Publications, Switzerland.
LFT Import::2019-08-05 (1581)
Keywords: Bending; Roll forming; Ultra-high-strength steel

Ultraschallunterstütztes Umformen und Verstemmen - Aktuelle Ergebnisse aus dem Verbundprojekt "UltraCaulk" - Leicht, U.; Michalski, Markus; Merklein, Marion (wt Werkstattstechnik - Online, 2017)
Substantial force reductions can be achieved by superimposing high frequency oscillation on forming processes. The joint research project UltraCaulk focusses on fundamental investigations on the material flow behaviour during ultrasonic influence and the transferability of identified mechanisms on industrial caulking processes. This study analyses the influence of process parameters on the resulting force reduction and specimen heating.
LFT Import::2019-07-29 (2199)

Ultraschallunterstützte Umformung von Metallen - Entwicklung eines Prüfstands zur Werkstoffcharakterisierung mit 15 kHz Schwingungsüberlagerung - Michalski, Markus; Merklein, Marion (wt Werkstattstechnik - Online, 2015)
LFT Import::2019-07-29 (2120)

Ultrasonic-assisted forming - Influence of unavoidably induced tool oscillations - Jäckisch, Manuel; Merklein, Marion (XL. Conference on Metal Forming, 2022)
Enhanced material strengths and a growing demand for complex part geometries lead to elevated process forces in cold forming processes and in turn to increased tool wear. One approach to face these challenges is the application of ultrasonic-assistance. By superimposing a high frequency oscillation to the tool movement, the material’s flow stress is reduced immediately and forming with lower process forces is feasible. This beneficial softening enhances with increasing vibrational energy input. Thus, the oscillation amplitude has been determined as the crucial process parameter for the achievable force reduction. When superimposing the punch with a high frequency oscillation, the vibration is introduced not only into the workpiece itself, but also through it into the fixed die. Consequently, moderate unavoidable oscillations occur in the fixed tool. In dependency of the phase shift between the oscillating tools, the nominal amplitude can be amplified or weakened. Nevertheless, most studies focused merely on the nominal amplitude. Within this contribution ultrasonic-assisted compression testing with pure copper Cu-OFE and brass CuZn37 is carried out and the oscillations of the upper and lower tool are measured synchronously. Significant deviations between the introduced and the effective oscillation are determined, leading to alternated process parameters.<br
Keywords: ultrasonic; metal forming; measurement; tool

Ultrasonic-Assisted Upsetting of Steel with 15 kHz Oscillation Frequency - Michalski, Markus; Merklein, Marion (Key Engineering Materials, 2016)
LFT Import::2019-07-29 (2170)
Keywords: Cold Forming; Metal; Ultrasonic

Ultrasound-assisted material characterization: An innovative method for the non-destructive in-situ detection of microstructural changes of high-strength aluminum alloys - Rigas, Nikolaos; Lypchanskyi, Oleksandr; Prahl, Ulrich; Merklein, Marion (Journal of Materials Processing Technology, 2024)
The use of aluminum alloys in conjunction with thermal-assisted forming techniques permits the production of high-strength and geometrically complicated components without failure. By using innovative, temperature-dependent production techniques, it is possible to manufacture components with tailored properties. So far, however, it is not possible to characterize the microstructural behavior under thermal and mechanical load in real-time. Using a novel characterization method, which is based on the principle of laser ultrasonic testing, it has become possible to record contact-free and non-destructive microstructural changes in-situ during thermo-mechanical treatment. This allows the interaction-free detection of thermal as well as mechanical effects during thermal-supported forming operations. In this research work, the temperature-dependent behavior during the quenching and aging process of the precipitation-hardenable aluminum alloy AA6082 for a tailor-quenched forming process is recorded in real-time using laser ultrasonic techniques. First, the effects of different tool temperatures on quenching rates and material properties were investigated using conventional characterization methods, including temperature measurement, hardness and tensile tests. It was shown that a die temperature of 325 °C leads to the lowest material hardness and strength. Subsequently, the results were compared with the novel, non-destructive in-situ testing method and validated using microstructural analysis. It was proven, that microstructural changes can be identified during varying quench and aging operations. Thus, the influence of different process parameters on the microstructural and mechanical development of aluminum components can be detected in-situ for the first time.
Keywords: Tailor Quenched Forming; High-strength aluminum; In-situ characterization; LUMet; Precipitation behavior

Umformen von Magnesiumblechen im Doppelpack - Merklein, Marion; Hußnätter, Wolfgang (Maschinenmarkt, 2007)
LFT Import::2019-07-16 (1400)

Umformtechnische Herstellung von Funktionsbauteilen aus Tailored Blanks durch Blechmassivumformverfahren - Schulte, Robert Karl; Lechner, Michael; Vogel, Manfred; Hildenbrand, Philipp; Merklein, Marion (22. Umformtechnisches Kolloquium Hannover – Innovationspotentiale in der Umformtechnik. 15./16.03.2017, 2017)
LFT Import::2019-08-05 (2230)

Umform- und Rückfederungssimulation von Leichtbauwerkstoffen - Vergleichende Betrachtung von Zug-Druck- und Wechselbiegeversuchen zur Berücksichtigung des Bauschinger-Effekts - Wieland, Michael; Kaupper, Markus; Merklein, Marion (Tagungsband des 33. EFB-Kolloquiums Blechverarbeitung, 2013)
LFT Import::2019-08-05 (1887)

Umformung von Tailored Heat Treated Blanks aus Aluminium - Merklein, Marion; Geiger, Manfred (Metall, 2006)
LFT Import::2019-07-16 (1300)

Umformwerkzeuge in der Blechmassivumformung - Biermann, D.; Merklein, Marion; Engel, Ulf; Tillmann, W.; Surmann, T.; Hense, R.; Herper, J.; Koch, Johannes Peter Karl; Krebs, E.; Vierzigmann, Ulrich (1. Workshop Blechmassivumformung, 2011)
LFT Import::2019-08-05 (1777)

Unsupervised Deep Learning for Advanced Forming Limit Analysis in Sheet Metal: A Tensile Test-Based Approach - Thamm, Aleksandra; Thamm, Florian; Sawodny, Annette; Zeitler, Sally; Merklein, Marion; Maier, Andreas (Materials, 2023)
An accurate description of the formability and failure behavior of sheet metal materials is essential for an optimal forming process design. In this respect, the forming limit curve (FLC) based on the Nakajima test, which is determined in accordance with DIN EN ISO 12004-2, is a wide-spread procedure for evaluating the formability of sheet metal materials. Thereby the FLC is affected by influences originating from intrinsic factors of the Nakajima test-setup, such as friction, which leads to deviations from the linear strain path, biaxial prestress and bending superposition. These disadvantages can be circumvented by an alternative test combination of uniaxial tensile test and hydraulic bulge test. In addition, the forming limit capacity of many lightweight materials is underestimated using the cross-section method according to DIN EN ISO 12004-2, due to the material-dependent occurrence of multiple strain maxima during forming or sudden cracking without prior necking. In this regard, machine learning approaches have a high potential for a more accurate determination of the forming limit curve due to the inclusion of other parameters influencing formability. This work presents a machine learning approach focused on uniaxial tensile tests to define the forming limit of lightweight materials and high-strength steels. The transferability of an existing weakly supervised convolutional neural network (CNN) approach was examined, originally designed for Nakajima tests, to uniaxial tensile tests. Additionally, a stereo camera-based method for this purpose was developed. In our evaluation, we train and test materials, including AA6016, DX54D, and DP800, through iterative data composition, using cross-validation. In the context of our stereo camera-based approach, strains for different materials and thicknesses were predicted. In this cases, our method successfully predicted the major strains with close agreement to ISO standards. For DX54D, with a thickness of 0.8 mm, the prediction was 0.659 (compared to ISO’s 0.664). Similarly, for DX54D, 2.0 mm thickness, the predicted major strain was 0.780 (compared to ISO 0.705), and for AA6016, at 1.0 mm thickness, a major strain of 0.314 (in line with ISO 0.309) was estimated. However, for DP800 with a thickness of 1.0 mm, the prediction yielded a major strain of 0.478 (as compared to ISO 0.289), indicating a divergence from the ISO standard in this particular case. These results in general, generated with the CNN stereo camera-based approach, underline the quantitative alignment of the approach with the cross-section metho
Keywords: forming limit curve; pattern recognition; sheet metal forming; machine learning

Untersuchung der Reibbedingungen beim Presshärten mittels Streifenziehversuchen bei erhöhten Temperaturen - Schwingenschlögl, Patrik; Hildering, Sven; Merklein, Marion (10. Erlanger Workshop Warmblechumformung, 2015)
LFT Import::2019-08-05 (2129)

Untersuchung der thermo-mechanischen Fließeigenschaften presshärtbarer Stähle - Merklein, Marion; Lechler, Jürgen; Geiger, Manfred; Kleiner, M.; Karbasian, H.; Homberg, W. (Proceedings of the 2nd International Conference on Accuracy in Forming Technology ICAFT 2006, in Verbindung mit 13. sächsische Fachtagung Umformtechnik SFU 2006, 2006)
LFT Import::2019-08-05 (1341)

Untersuchung der Werkzeugbeanspruchung und des Verschleißes beim Schneidclinchen - Wiesenmayer, Sebastian; Han, D.; Meschut, G.; Merklein, Marion (XXXVIII. Verformungskundliches Kolloquium, 2019)
LFT Import::2019-08-05 (2360)

Untersuchung des Einflusses von Chargenschwankungen auf das Umwandlungsverhalten übereutektoider Stähle - Lutz, Stefan; Weninger, J.; Helldörfer, B.; Merklein, Marion (Tagungsband Werkstoffprüfung, 2014)
LFT Import::2019-08-05 (2063)

Untersuchung des Einflusses von werkstückseitigen Parametern auf die Schichtausbildung von zinkbeschichtetem Bor-Manganstahl - He, Franz; Merklein, Marion (Warmumformung von höchstfesten Vergütungsstählen: Tagungsband zum 16. Erlanger Workshop Warmblechumformung, 2021)
Das Presshärteverfahren hat sich als Technologie zur Herstellung von höchstfesten Stahlwerkstoffen für sicherheitsrelevante Bauteile im Karosserieleichtbau etabliert. Durch ihren Einsatz lassen sich aufgrund reduzierter Blechdicke in Kombination mit hohen Zugfestigkeiten Leichtbaukonzepte bei gleichzeitig verbessertem Crashverhalten realisieren. Dabei kommen für gewöhnlich Bor-Mangan-Stähle zum Einsatz. Aufgrund von Prozesstemperaturen über 800 °C gilt das Presshärten als schmierstofffreies Verfahren. Neben hoher Reibung und Verschleiß im Prozess sind Oberflächenverzunderung und Nachbearbeitung die Folge. Zum Schutz vor Korrosion werden Presshärtewerkstoffe deswegen beschichtet. Bisher kamen hauptsächlich Beschichtungen auf Aluminium-Silizium-Basis für das direkte Presshärten zum Einsatz. Während Beschichtungen auf Zink-Basis bisher vorwiegend im indirekten Prozessablauf Anwendung fanden, erschließt sich diese inzwischen auch für die direkte Verfahrensroute. In vorherigen Untersuchungen konnte für Aluminium-Silizium (AlSi) Beschichtungen ein signifikanter Einfluss von werkstückseitigen Parametern auf die Ausbildung der Beschichtung während des Austenitisierungsprozesses festgestellt werden. Vor diesem Hintergrund wird ein ähnlich signifikanter Einfluss für Beschichtungen auf Zink-Basis vermutet. Im Zuge dessen sollen die Parameter Aufheizrate, Ofentemperatur und Ofenverweilzeit und die Auswirkung auf die Schichtausbildung von zinkbeschichteten 20MnB8 während der Austenitisierung untersucht werden. Die sich daraus ergebenden Erkenntnisse bilden die Basis für weiterführende Versuche, um den tiefergehenden Einfluss der Parameter auf Reibung und Verschleiß im industrienahen Streifenzugversuch zu untersuchen. <
Keywords: Zinkbeschichtung; 20MnB8; Direktes Presshärten

Untersuchung des Einsatzverhaltens kaltfließgepresster Zahnräder - Rohrmoser, Andreas; Kiener, Christoph; Hagenah, Hinnerk; Merklein, Marion (34. Jahrestreffen der Kaltmassivumformer, 2019)

Untersuchung des tribologischen Einsatzverhaltens von lokal dispergierten Presshärtewerkzeugoberflächen - Schirdewahn, Stephan; Spranger, Felix; Hilgenberg, Kai; Merklein, Marion (14. Erlanger Workshop Warmblechumformung, 2019)
Das Presshärteverfahren hat sich zur ressourceneffizienten Verarbeitung von höchstfesten Stahlwerkstoffen im Karosserieleichtbau weltweit etabliert. Die fehlerfreie Bauteilproduktion wird jedoch durch Reibungs- und Verschleißerscheinungen aufgrund hoher thermo-mechanischer Werkzeugbelastungen und fehlender Schmierstoffsysteme limitiert. Als Lösungsansatz wird eine Modifikation der Werkzeugoberfläche mittels Laserimplantation angestrebt, um folglich deren Verschleißbeständigkeit nachhaltig zu erhöhen. Das Verfahren basiert auf einem lokalen Dispergieren keramischer Hartstoffpartikel in die Werkzeugoberfläche, infolgedessen hochfeste und erhabene Strukturen im Mikrometerbereich entstehen. Aufgrund der signifikanten Reduzierung der Kontaktfläche sowie der hohen Verschleißbeständigkeit der eingesetzten TiB2-Hartstoffe wird ein verbessertes tribologisches Einsatzverhalten unter presshärtetypischen Prozessbedingungen erwartet. Zur Verifizierung dieser Annahmen wurden im Rahmen dieser Arbeit modifizierte Pin-on-Disk Tests durchgeführt, um das Reib- und Verschleißverhalten der laserimplantierten Werkzeugoberflächen unter Presshärtebedingungen zu untersuchen. Zur weiteren Vertiefung des Prozess-verständnisses wurden die verschlissenen Platinen via Tastschnittmessungen und Querschliffaufnahmen analysiert. Durch den Ergebnisvergleich mit konventionellen Werkzeugoberflächen erfolgte eine abschließende Bewertung des tribologischen Einsatzverhaltens der laserimplantierten Strukturen.<br
Keywords: Presshärten; Laserimplantation; Tribologie; 22MnB5

Untersuchungen hinsichtlich der Eignung von EN AW 1050 für die Herstellung prismatischer Bauteile mittels Napf-Rückwärts-Fließpressen - Austen, M.; Klonczynski, A.; Derenthal, M.-J.; Noneder, Johannes; Merklein, Marion (UTF-Science, 2013)
LFT Import::2019-07-29 (1906)

Untersuchungen von Tailored Surfaces für die Blechmassivumformung mittels angepasstem Ringstauchversuch - Vierzigmann, Ulrich; Schneider, Thomas; Koch, Johannes Peter Karl; Gröbel, Daniel; Merklein, Marion; Engel, Ulf; Hense, R.; Biermann, D.; Krebs, P.; Kersting, P.; et al. (2. Workshop Blechmassivumformung, 2013)
LFT Import::2019-08-05 (1926)

Use of elastomers as pressure media for fatigue testing of cold forging tools - Killmann, Martin; Merklein, Marion (Procedia Structural Integrity, 2023)
Cold forging has high potential as a sustainable production technology. With net-shape production, only the material needed for the produced part is used. By not heating up the workpiece, energy consumption is also low. However, this leads to high forming forces and consequently critical stresses in the tools. An accurate prediction of tool life is therefore necessary; both to find measures for its increase and to plan tool changes with minimal machine downtime. Currently there is little data about the fatigue properties of cold forging tool materials. Existing tests to determine this data strongly simplify the tools’ stress state to a uniaxial load. Therefore, a new fatigue test is presented in this paper, which incorporates the actual load conditions of cyclically swelling inner pressures. For this purpose, a high-strength elastomer is used as pressure medium. Its low compressibility and high elasticity allow for cyclic testing with pressures up to at least 2000 MPa. This load causes wear on the elastomer, as it is pressed into the gap between the punch used to apply the load and the fatigue specimen. Therefore, the gap between punch and fatigue specimen should be as low as possible to ensure stable test conditions. Within the scope of the research, fatigue failure already occurred in one specimen. This shows that the compression of elastomers is able to generate very high loads comparable to the cold forging of steel. <
Keywords: Fatigue; Elastomer; Metal Forming

Use of FEM and DoE to reduce the forming force during cold extrusion of prismatic cell housings - Austen, Michael; Noneder, Johannes; Merklein, Marion (Key Engineering Materials, 2014)
These days, the call for more efficient cars, e.g. EURO 6, to reduce substantial the emissions of carbon dioxide and nitrous oxide raises the demand and development for Battery Electric Vehicles (BEV) or Plug-in Hybrid Electric Vehicles (PHEV). Thus, the German Government in cooperation with the industry has the goal to get at least 6 million electric vehicles on German streets by the year 2030. Until today battery systems increase the car's weight significantly, therefore weight reduction and utilization of the required space are two of the most important strategies. Because of its low density and high formability aluminum is preferred as cell housing material. Besides a light material it is necessary to use the required space of the battery pack in the car as efficient as possible. Thus a prismatic shape is favored compared to a cylindrical one. Unfortunately a prismatic cell causes an asymmetric material flow and an asymmetric tool loading during the production via bulk metal forming as the material tends to flow into the direction of the larger edges of the housing walls. That is why new forming tools for bulk forming have to be developed. To do this economically the development will be done by using design of experiments (DoE) and the finite element method (FEM). On the one hand DoE shortens time-consuming FE-simulations by stating exactly which simulations need to be done to identify main determining factors for the personal command variable(s) e.g. tool lifetime. On the other hand FEM can be used to achieve simulation results, e.g. tool loading, which are comparable to real life experiments. By using DoE, 2D FE-simulations show that the geometry of the punch's extrusion shoulder can decrease the required forming force precisely. In addition the geometry of so called deceleration seams can affect the forming force in minor degree. In combination of all significant geometric parameters and the number and position of deceleration seams the tool loading of a cold extrusion punch could be reduced significantly. © 2014 Trans Tech Publications, Switzerland.
LFT Import::2019-07-29 (2014)
Keywords: Bulk metal forming; Cold extrusion; DoE; FEM; Forming force; Prismatic cell housings; Simulation

Use of Monocrystalline Silicon as Tool Material for Highly Accurate Blanking of Thin Metal Foils - Hildering, Sven; Engel, Ulf; Merklein, Marion (AIP Conference Proceedings, 2011)
The trend towards miniaturisation of metallic mass production components combined with increased component functionality is still unbroken. Manufacturing these components by forming and blanking offers economical and ecological advantages combined with the needed accuracy. The complexity of producing tools with geometries below 50 μm by conventional manufacturing methods becomes disproportional higher. Expensive serial finishing operations are required to achieve an adequate surface roughness combined with accurate geometry details. A novel approach for producing such tools is the use of advanced etching technologies for monocrystalline silicon that are well-established in the microsystems technology. High-precision vertical geometries with a width down to 5 μm are possible. The present study shows a novel concept using this potential for the blanking of thin copper foils with monocrystallline silicon as a tool material. A self-contained machine-tool with compact outer dimensions was designed to avoid tensile stresses in the brittle silicon punch by an accurate, careful alignment of the punch, die and metal foil. A microscopic analysis of the monocrystalline silicon punch shows appropriate properties regarding flank angle, edge geometry and surface quality for the blanking process. Using a monocrystalline silicon punch with a width of 70 μm blanking experiments on as-rolled copper foils with a thickness of 20 μm demonstrate the general applicability of this material for micro production processes. © 2011 American Institute of Physics.
LFT Import::2019-07-29 (1621)
Keywords: accuracy; blanking; machine design; Microforming; monocrystalline silicon

Validation of kinematic hardening parameters from different stress states and levels of plastic strain with the use of the cyclic bending test - Rosenschon, Martin; Suttner, Sebastian; Merklein, Marion (Key Engineering Materials, 2015)
The recent development of new lightweight sheet metal materials, like advanced highstrength steels or aluminium alloys, in combination with an increasing component complexity provides new challenges to the numerical material modelling in the FEM based process design. An auspicious approach to improve the quality of the numerical results - most notably in springback analysis - is the modelling of the so called Bauschinger effect achieved through implementation of kinematic hardening models. Within this paper the influence of the stress state and the level of prestrain on the numerical simulation result of the advanced high strength steel DP-K45/78+Z will be analysed. For this purpose, a parameter identification of the kinematic hardening law according to Chaboche and Rousselier is performed at different pre-strains on the basis of experimental data from tension-compression tests as well as cyclic shear tests. Finally, the identified parameters are validated in a comparison between numerical and experimental results of a cyclic bending test.
LFT Import::2019-07-29 (2089)
Keywords: Kinematic hardening; Metal forming; Modelling

Variation of deep drawing steel grades’ properties in dependency of the stress state and its impact on FEA - Sturm, Vera; Merklein, Marion (International Journal of Material Forming, 2011)
LFT Import::2019-07-29 (1639)

Verbesserter Materialfluss beim Tiefziehen von Aluminiumblechen durch lokale Laserwärmebehandlung - Kerausch, Michael; Merklein, Marion; Geiger, Manfred (Tagungsband zum XXII. Verformungskundlichen Kolloquium, 2003)
LFT Import::2019-08-05 (951)

Verbesserung der Umformbarkeit von Aluminium - Graser, Matthias; Degner, Julia; Böhm, Wolfgang; Merklein, Marion (Konstruktion, 2017)
CRIS-Team Scopus Importer:2023-03-29

Verbesserung des tribologischen Einsatzverhaltens von Presshärtewerkzeugen durch Laserimplantation titanbasierter Hartstoffpartikel - Schirdewahn, Stephan; Spranger, Felix; Hilgenberg, Kai; Merklein, Marion (15. Erlanger Workshop Warmblechumformung, 2020)
In der Automobilindustrie stellt das Presshärteverfahren eine Schlüsseltechnologie zur ressourceneffizienten Herstellung sicherheitsrelevanter Karosseriekomponenten dar. Während der Umformoperation treten jedoch hohe Reibungsund Verschleißerscheinungen an den interagierenden Werkzeug- und Werkstückwirkflächen auf, die sowohl die Bauteilqualität als auch die Maschinenstandzeit nachhaltig beeinträchtigen. Um die bestehenden Verfahrensgrenzen zu erweitern, wird daher eine Modifikation der Presshärtewerkzeuge mittels Laserimplantation angestrebt. Hierbei werden in die Werkzeugoberfläche keramische Hartstoffpartikel anhand eines gepulsten Laserstrahles eingebettet, infolgedessen kuppelförmige sowie höchstfeste Strukturen im Mikrometerbereich entstehen. Die Auswahl geeigneter Hartstoffmaterialien stellt jedoch ein entscheidendes und bisweilen limitierendes Kriterium dar, um defektfreie sowie verschleißresistente Oberflächenmodifikationen zu generieren. In diesem Zusammenhang wurden im Rahmen dieser Arbeit unterschiedliche titanbasierte Hartstoffpartikel auf presshärtespezifische Werkzeugstähle laserimplantiert und anschließend mittels modifizierten Pin-on- Disk-Tests hinsichtlich ihres tribologischen Einsatzverhaltens untersucht. Um die Wirksamkeit des Laserimplantationsverfahrens zu evaluieren, wurden zudem Verschleißuntersuchungen an unmodifizierten Werkzeugoberflächen durchgeführt und mit den erzielten Ergebnissen der lokal dispergierten Topographien verglichen.<br
Keywords: Laserimplantation; Tribologie; Werkzeugmodifikation; Presshärten

Verfahrenskombination zur umformtechnischen Herstellung von verzahnten, dünnwandigen Funktionselementen aus prozessoptimierten Halbzeugen - Vogel, Manfred; Schulte, Robert Karl; Hetzel, Andreas; Lechner, Michael; Merklein, Marion (Aktuelle Entwicklungen im Bereich der Umformtechnik - 23. Umformtechnisches Kolloquium Hannover, 2020)
Konventionelle Blech- und Massivumformverfahren stoßen heute insbesondere im Automobilbereich, bedingt durch stetig steigende Ansprüche an Ressourceneffizienz und Funktionsintegration, oft an ihre Grenzen. Die Forderung nach verkürzten Prozessketten erhöht den Bedarf nach einer Erweiterung bestehender Prozessgrenzen zusätzlich. Ein Ansatz zur Bewältigung dieser Herausforderungen ist der Einsatz der innovativen Prozessklasse der Blechmassivumformung (BMU), welche durch die Anwendung von Massivumformoperationen auf Blechhalbzeuge definiert ist. Charakteristisch für diese Prozessklasse ist das Auftreten von dreidimensionalen Spannungs- und Dehnungszuständen, welche sowohl ein Ausdünnen als auch ein Aufdicken der Ausgangsplatine zulassen. Um die angestrebten Bauteileigenschaften realisieren zu können, ist der Aufbau eines grundlegen Prozessverständnisses zur gezielten Steuerung des Materialflusses unumgänglich. Für eine Steigerung der Materialflusskontrolle sowie einer Verbesserung der Bauteileigenschaften, werden im Teilprojekt A1 des Sonderforschungsbereiches Transregio 73 prozessangepasste Halbzeuge ausgelegt, umformtechnisch gefertigt und zu Funktionsbauteilen weiterverarbeitet. Die Halbzeugherstellung erfolgt dabei auf zwei unterschiedlichen Prozessrouten. Einsatz finden hierfür ein flexibler Walzprozess, sowie ein Taumelprozess, welche die Herstellung von Halbzeugen mit gradierten geometrischen und mechanischen Eigenschaften erlauben. Diese werden anschließend einstufigen Verfahrenskombination aus Tiefziehen und Stauchen zu Bauteilen mit Verzahnungs- und Mitnehmerelementen umgeformt. Wesentliche grundlagenwissenschaftliche Erkenntnisse des Projekts werden aktuell im Transferprojekt T02 zusammen mit Projektpartnern aus der Industrie in die Anwendung übertragen

Verfahren und Simulation zur umformtechnischen Charakterisierung von Tailored Hybrid Blanks - Geiger, Manfred; Merklein, Marion; Staud, Detlev; Giera, Artur (Berichtskolloquium der DFG-Forschergruppe 505, 2005)
LFT Import::2019-08-05 (1243)

Verformungsabhängiges Umwandlungsverhalten von presshärtbaren Bor-Mangan-Stählen - Merklein, Marion; Lechler, Jürgen; Svec, Thomas (4. Erlanger Workshop Warmblechumformung, 2009)
LFT Import::2019-08-05 (228)

Vergleich verschiedener Verfahren zur Fließkurvenaufnahme im Hinblick auf die Prozess- und Werkzeugauslegung bei der Kaltmassivumformung druckaufgestickter Stähle - Noneder, Johannes; Merklein, Marion; Engel, Ulf (Proceedings AutoMetFORM / SFU 2010, 2010)
LFT Import::2019-08-05 (745)

Verification of the Accuracy of FE-Models in Bulk-Forming of Micropins from Sheet Metal - Kraus, Martin; Hufnagel, Thomas; Merklein, Marion (WCMNM 2018 World Congress on Micro and Nano Manufacturing, doi: 10.3850/978-981-11-2728-1_02, 2018)
LFT Import::2019-08-07 (2307)

Verification of the Accuracy of FE-Models in Bulk-Forming of Micropins from Sheet Metal - Kraus, Martin; Hufnagel, Thomas; Merklein, Marion (World Congress on Micro and Nano Manufacturing - WCMNM 2018, 2018)

Verknüpfung additiver Fertigung und Umformtechnik in Form hybrider Bauteile und Werkzeuge. - Papke, Thomas; Junker, Daniel; Huber, Florian; Hentschel, Oliver; Schmidt, Michael; Merklein, Marion (Tagungsband Fachtagung Werkstoffe und Additive Fertigung, 2018)
LFT Import::2019-08-05 (2297)

Vernetzte Fertigung - Berücksichtigung der Herstellungshistorie von Blechbauteilen beim Fügen durch Umformen - Wiesenmayer, Sebastian; Heyser, Per; Nehls, Thomas; Frey, Philipp; Flügge, Wilko; Meschut, Gerson; Merklein, Marion (wt Werkstattstechnik - Online, 2020)
Sheet metal components are manufactured in various cutting and forming operations influencing the resulting properties of the parts. As these properties differ from the initial state of the semi-finished products, they have to be considered in the design of clinched joints. By connecting individual processes, this paper presents an approach for determining the properties of semi-finished parts in shear-cutting operations as well as their effects on the joint quality in clinching.

Versagensanalyse nach Vorbelastung in einer Ziehsicke - Schmid, Harald; Merklein, Marion (EFB-Kolloquium Blechverarbeitung: Wirtschaftliche Verarbeitung hochfester Werkstoffe für Leicht- und Funktionsbau, 2019)
LFT Import::2019-08-05 (2365)

Versagensanalyse unter prozessnaher Vorbelastung durch überlagerte Zug- und Wechselbiegebelastung - Merklein, Marion; Schmid, Harald (2019)

Verschleißeigenschaften unbeschichteter und beschichteter Werkzeuge in Abhängigkeit unterschiedlicher Werkzeugbeanspruchungen - Wieland, Michael; Merklein, Marion (5. Erlanger Workshop Warmblechumformung, 2010)
LFT Import::2019-08-05 (747)

Verschleißmodellierung am Beispiel einer Polyamid-Stahl-Getriebepaarung für das prozessorientierte Toleranzmanagement - Schubert, Dominik; Rohrmoser, Andreas; Hagenah, Hinnerk; Merklein, Marion; Drummer, Dietmar (Beiträge zur 4. Summer School, 2020)

Virtuelle Analysetools – Eine smarte Methode zur effizienten Erforschung von Kaltfließpressprozessen - Kiener, Christoph; Merklein, Marion (Konstruktion, 2017)
Gears are integral and vital machine elements in the field of drive and transmission technology. With regard to economic and ecological aspects, cold forging represents a promising approach compared to conventional cutting processes for producing highly-loadable gears. The achievable gear accuracy as well as an insufficient tool life is one major challenge during establishing cold forging processes in industry. Thus, the use of numerical analysis tools offers a great potential for an efficient and effective process research.
LFT Import::2019-07-29 (2263)

Warmforming Flow Pressing Characteristics of Continuous Fibre Reinforced Thermoplastic Composites - Gröger, Benjamin; Römisch, David; Kraus, Martin; Troschitz, Juliane; Füßel, René; Merklein, Marion; Gude, Maik (Polymers, 2022)
The paper presents research regarding a thermally supported multi-material clinching process (hotclinching) for metal and thermoplastic composite (TPC) sheets: an experimental approach to investigate the flow pressing phenomena during joining. Therefore, an experimental setup is developed to compress the TPC-specimens in out-of-plane direction with different initial TPC thicknesses and varying temperature levels. The deformed specimens are analyzed with computed tomography to investigate the resultant inner material structure at different compaction levels. The results are compared in terms of force-compaction-curves and occurring phenomena during compaction. The change of the material structure is characterized by sliding phenomena and crack initiation and growt
Keywords: thermoplastic composite; clinching; joining; material behaviour; FEM; compaction

warm hydroforming of magnesium sheets? results and microstructural changes - Geiger, Manfred; Merklein, Marion; Hecht, Joachim (Proceedings of the 8th International Conference on Technology of Plasticity (ICTP), 09.-13.10., Verona, Italy, 2005)
LFT Import::2019-08-05 (1217)

Wear Analysis of Micro Textured Coining Tools - Reck, Manuel; Merklein, Marion (XLI. Colloquium on Metal Forming, 2023)

Wear behavior of PVD-Coatings - Merklein, Marion; Schrader, Tobias; Engel, Ulf (Tribology in Industry, 2012)
In cold forging high tribological loads often lead to premature tool failure. If the cause of failure is wear, an extension of tool life can be achieved by applying PVD coatings. According to the different load cases appearing in cold forging processes, the development of a great variety of coatings with different properties is crucial for adjusting their properties to the plurality of applications. In order to investigate the developed coatings concerning their suitability for different processes, a sufficient characterization of the coatings is required. In this paper six different PVD coatings are investigated in the three-ball-on-disc test giving a basic impression towards wear behavior of the coatings and predominant wear mechanisms. © 2012 Published by Faculty of Engineering.
LFT Import::2019-07-29 (1814)
Keywords: Coatings; PVD; Wear

Wear Behavior of Uncoated and Coated Tools under Complex Loading Conditions - Wieland, Michael; Merklein, Marion (Tribology in Industry, 2012)
In automotive industry crash relevant structures of the body in white are manufactured using the direct hot stamping process. Due to the high temperature difference between the hot blank and the cold tool surfaces and the relative movement between the blank and the tool surfaces during the forming operation, high thermal and mechanical loads are applied on the tool leading to excessive wear in terms of adhesion on the tool surfaces. One possibility to reduce wear of hot stamping tools is the application of tool coating systems. In the scope of this work uncoated and coated tools are characterized under complex loading conditions with respect to adhesive layer build-up. © 2012 Published by Faculty of Engineering.
LFT Import::2019-07-29 (1805)
Keywords: Adhesive Wear; AlCrN-coating; Hot stamping; Sheet-bulk metal forming

Wear Behavior of Uncoated and Coated Tools Used for Direct Hot Stamping - Wieland, Michael; Merklein, Marion (2nd International Conference of Engineering Against Fracture, 2011)
LFT Import::2019-08-05 (1735)

Wear Behavior of Uncoated and Coated Tools With Respect to Different Loading Conditions - Wieland, Michael; Merklein, Marion (Proc. 3rd Int. Conf. Hot Sheet Metal Forming of High-Performance Steel, 2011)
LFT Import::2019-08-05 (1737)

Weiterführende Untersuchungen zum Fließverhalten presshärtbarer Stähle - Stöhr, Thomas; Merklein, Marion (Tagungsband 4. Erlanger Workshop Warmblechumformung, 2009)
LFT Import::2019-08-05 (217)

Werkstoffcharakterisierung mit Blick auf die Vergangenheit, die Gegenwart und die Zukunft - Merklein, Marion; Suttner, Sebastian (Tagungsband - 20. Sächsiche Fachtagung Umformtechnik, 2013)
LFT Import::2019-08-05 (1921)

Werkstoffgerechte Bauteil- und Prozessauslegung in der Blechumformung - Merklein, Marion; Geiger, Manfred; Vogt, Uwe (Neuere Entwicklungen in der Blechumformung: Tagungsband, Stuttgart: Werkstoff-Informationsgesellschaft, 2006)
LFT Import::2019-08-05 (1301)

Werkstoffschädigung in der Prozesskette Schneiden - Biegen - Tsoupis, Ioannis; Hildering, Sven; Hagenah, Hinnerk; Merklein, Marion (17. Workshop Simulation in der Umformtechnik, 2014)
LFT Import::2019-08-05 (1945)

Werkstückseitige Beeinflussung und Modellierung der tribologischen Bedingungen beim Presshärten - He, Franz; Merklein, Marion (2022)
Das Auftreten von Reibung und Verschleiß stellt eine akute Herausforderung im Presshärteprozess dar, da aufgrund von erhöhten Prozesstemperaturen > 850 °C der Einsatz von Schmierstoffen nicht möglich ist. Die tribologischen Bedingungen in der Wirkfuge zwischen Werk- und Halbzeug bilden dabei eine kritische Komponente im Prozess, die sowohl die Werkzeugstandzeit als auch finale Produktqualität maßgeblich beeinflusst. Während im vorangegangenem Projekt P1228/19337 „Werkzeugseitige Beeinflussung der tribologischen Bedingungen beim Presshärten“ die werkzeugseitigen Einflussfaktoren auf den Presshärteprozess untersucht wurden, zeigen bisherige Forschungsarbeiten, dass die werkstückseitig eingesetzte Beschichtung im Halbzeug einen maßgeblichen Einfluss auf die auftretenden Reib- und Verschleißmechanismen haben. Die Zielsetzung des Forschungsvorhabens besteht darin, funktionale Wirkzusammenhänge zwischen den Austenitisierungsparametern und der Schichtausbildung sowie dem tribologischen Einsatzverhalten von Beschichtungswerkstoffen beim Presshärten zu ermitteln. Durch das Verständnis der Wirkzusammenhänge werden Maßnahmen abgeleitet, welche die Standzeit von Presshärtewerkzeugen und somit die Wirtschaftlichkeit des Prozesses erhöhen. Um das Forschungsziel zu erreichen, wurden in Absprache mit den Industriepartnern zwei Werkstückwerkstoffe mit unterschiedlichen Beschichtungen für die Untersuchungen ausgewählt. Darüber hinaus wurden unterschiedliche Austenitisierungsparameter und deren Einfluss auf die resultierende Ausbildung der Beschichtung analysiert. Die Ergebnisse dienten dazu, signifikante Parameter zu identifizieren und deren Einfluss auf Reibung und Verschleißverhalten auf Basis des Streifenziehversuchs zu untersuchen. Die Untersuchungen haben gezeigt, dass die Austenitisierungsparameter im Rahmen der Laborversuche keine Auswirkung auf das resultierende Reibverhalten haben. Jedoch kann sowohl die Wahl des Werkstückwerkstoffes als auch dessen Beschichtung einen Einfluss auf das tribologische Verhalten haben. Die Ergebnisse wurden in Form eines Reibzahlmodells konsolidiert und als mathematische Gleichung zur Verfügung gestel

Werkzeugherstellung in der Kaltmassivumformung - Einfluss der Werkzeugoberfläche auf die tribologischen Bedingungen - Andreas, Kolja; Merklein, Marion; Engel, Ulf (wt Werkstattstechnik - Online, 2012)
LFT Import::2019-07-29 (1836)

Werkzeugseitige Beeinflussung der tribologischen Bedingungen beim Presshärten - Schwingenschlögl, Patrik; Hauser, D.; Tenner, Jennifer; Merklein, Marion (Tagungsband zum 12. Erlanger Workshop Warmblechumformung, 2017)
LFT Import::2019-08-05 (2275)

Werkzeug- und Halbzeugbeschichtungen für das direkte Presshärten - Wieland, Michael; Merklein, Marion; Geiger, Manfred (Moderne Beschichtungen zum Verschleißschutz von Werkzeugen, 2012)
LFT Import::2019-08-05 (1874)

Wirkmedienbasierte Umformng von Tailor Welded Blanks - Tolazzi, Massimo; Merklein, Marion; Geiger, Manfred (Wirkmedienbasierte Fertigungstechniken zur Blechumformung, Abschlussbereicht zum DFG-Schwerpunktprogramm SPP 1098, 28.-29.09., Dortmund, 2006)
LFT Import::2019-08-05 (1311)