Bachmann J, Göken M, Höppel HW (2018)
Publication Type: Book chapter / Article in edited volumes
Publication year: 2018
Publisher: Springer Spektrum
Edited Volumes: Fatigue of Materials at Very High Numbers of Loading Cycles
City/Town: Wiesbaden
Pages Range: 1-23
ISBN: 9783658245306
DOI: 10.1007/978-3-658-24531-3_1
The fatigue behaviour and damage evolution in body centered cubic low alloyed steels in the high cycle and very high cycle fatigue regimes (HCF/VHCF) were in focus of this work. For this purpose, the steels C15E, C45E and C60E, with different ferritic-pearlitic microstructures were investigated. Due to the different carbon contents the ratio of ferrite to pearlite decreased from C15E to C60E. C15E mainly consist of ferrite grains. The ferrite grains deform plastically under cyclic loading. With decreasing stress amplitudes plastic deformation becomes more and more localized in particular ferrite grains. During further cyclic loading plastic deformation accumulates in those grains and finally leads to crack initiation and fatigue failure. The accumulation of irreversible plastic deformation in the ferrite grains and the strength of microstructural barriers in the vicinity of the plastically deformed grains are mainly determining the total fatigue life. In order to assess quantitatively the contribution of irreversible plastic deformation a new method was developed. By determining the dissipated energy per fatigue cycle, which was derived from the power input of the ultrasonic fatigue machine, it is possible to account for the amount of irreversibility during one loading pulse. Based on these results a prediction of the fatigue life can be made at a very early stage of the fatigue experiment. It also allows distinguishing very early whether the specimen will become a runout or if it will fail at a given amplitude. It also turned out that the interaction of localized plastic deformation with microstructural barriers in the direct vicinity is the key for understanding the occurrence of late fatigue failure. If specimens showed macroscopic crack growth and fatigue failure, critical cracks always initiated at interfaces. On the other hand, runout specimens showed some crack nuclei, but they were not able to overcome the next microstructural barrier.
APA:
Bachmann, J., Göken, M., & Höppel, H.W. (2018). Fatigue of low alloyed carbon steels in the HCF/VHCF-regimes. In Hans-Jürgen Christ (Eds.), Fatigue of Materials at Very High Numbers of Loading Cycles. (pp. 1-23). Wiesbaden: Springer Spektrum.
MLA:
Bachmann, Jonas, Mathias Göken, and Heinz Werner Höppel. "Fatigue of low alloyed carbon steels in the HCF/VHCF-regimes." Fatigue of Materials at Very High Numbers of Loading Cycles. Ed. Hans-Jürgen Christ, Wiesbaden: Springer Spektrum, 2018. 1-23.
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