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Effect of wall thickness on heat flow conditions in directed energy deposition

Yang S, Goodall AD, Jin X, Shang X, Zou Y, Chechik L (2026)

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Publication Type: Journal article

Publication year: 2026

Journal

Book Volume: 260

Article Number: 128414

DOI: 10.1016/j.ijheatmasstransfer.2026.128414

Abstract

Heat flow conditions vary significantly in Directed Energy Deposition (DED), such as during the repair of structures with varying cross sections. While classical thermal analyses emphasize conduction, heat losses through convection and radiation can be consequential in thin-wall geometries. This can lead to certain geometries experiencing heat accumulation with build height, while in other geometries, the temperature decreases as the build height increases. To quantify how heat flow mechanisms vary with wall thickness, in this study, in-situ coaxial monitoring was combined with a finite element (FE) model that accounts for conduction, convection, and radiation. Measured melt pool thermal intensities during the deposition of 9 Inconel 718 walls with thicknesses ranging from thin- to thick-wall regimes are compared with FE-based predictions. The results show that conduction is the dominant heat transfer mechanism between the melt pool and the surrounding materials in all cases during deposition; however, convective and radiative losses of the melt pool are non-negligible in thin-wall regimes, being responsible for up to 35 % of the total heat losses. Meanwhile, the relative importance of convection/radiation of the melt pool was found to increase as sections narrow. In addition, the minimum heat loss of the melt pool (and the maximum thermal intensity) was observed at an intermediate wall thickness (2.1 mm), while the total heat losses of the melt pool increased by 39 % in a 1.1 mm wall thickness and by 17 % in a 9.1 mm wall thickness. These strongly non-linear thermal relationships lead to the conclusion that samples wider than 4 mm can be treated as “bulk”, for which conduction-dominated assumptions are adequate in thermal analysis; sections with a thickness less than 4 mm require convection and radiation to be considered. These findings could provide guidance in the selection of deposition parameters and modeling assumptions to ensure consistent DED repairs across highly variable cross-sections.

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APA:

Yang, S., Goodall, A.D., Jin, X., Shang, X., Zou, Y., & Chechik, L. (2026). Effect of wall thickness on heat flow conditions in directed energy deposition. International Journal of Heat and Mass Transfer, 260. https://doi.org/10.1016/j.ijheatmasstransfer.2026.128414

MLA:

Yang, Shenliang, et al. "Effect of wall thickness on heat flow conditions in directed energy deposition." International Journal of Heat and Mass Transfer 260 (2026).

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