Residual Stress in Metal Parts Produced by Powder-Bed Additive Manufacturing Processes

In this study, residual stresses from the electron beam additive manufacturing (EBAM) and selective laser melting (SLM) processes, due to repeated thermal cycles, were investigated. Residual stresses play a crucial role in part performance, and thus, it is critical to evaluate the process-induced residual stresses in AM parts. Ti-6Al-4V and Inconel 718 parts produced by EBAM and SLM, respectively, were studied in residual stresses using the methodology established by Carlsson et al., a mechanical instrumented indentation technique, which is based on the experimental correlation between the indentation characteristic and the residual stress. The results show that the Ti-6Al-4V EBAM parts have a compressive residual stress in both Z-plane and Xplane, while the Inconel 718 SLM parts show a tensile stress and a compressive stress in the Zplane and X-plane, respectively. Besides, the Ti-6Al-4V parts have lower absolute value of residual stress than the Inconel 718 parts. Moreover, the Vickers hardness values of the parts built using SLM and EBAM are comparable to the literature data.