Influence of laser power and scanning strategy on residual stress distribution in additively manufactured 316L steel

Residual stress control in the metal components by additive manufacturing (AM) has been a major challenge. To mitigate this challenge, proper selection of AM process parameters is of great importance. In this study, we investigate the influence of laser power and scanning strategies on residual stress distribution in 316L steel by a metal AM process, namely, selective laser melting (SLM). Finite element simulation and experimental verification are conducted by using the identical process parameters and part geometry to ensure that the results are indeed comparable and can shed light on the challenging issue of residual stress control. With two levels of laser power (i.e., 160 W and 200 W) and two scanning strategies (i.e., stripe scanning and chessboard scanning), four process conditions are investigated. For all four conditions, both simulation and experiment show that the tensile residual stress in the area of interest (the center area of each layer) tends to gradually increase along the depth into surface. Also, the increase of laser power from 160 W to 200 W and the adoption of stripe scanning (instead of chessboard scanning) generally lead to the increase of tensile residual stress in the area of interest. The trends are also confirmed by both simulation and experiment. In addition, the laser power increase from 160 W to 200 W appears to have more significant effect, compared with the switch of two scanning strategies.