Effect of scan strategy and substrate preheating on crack formation in IN738LC Ni-based superalloy during laser powder bed fusion

Manufacturing high-volume γ´-strengthened Ni-based superalloys by laser powder bed fusion process (LPBF) remains challenging due to the material's high susceptibility to cracking. This study explored the effects of scanning strategy and substrate preheating on the residual stress distribution and crack formation in LPBF-fabricated Ni-based superalloy IN738LC using non-destructive techniques such as X-ray diffraction and neutron diffraction. A three-dimensional finite element model was developed to numerically analyze the temperature field and thermal stress evolution. Crack-free IN738LC components were successfully produced by effectively managing thermal history and residual stress distribution during the LPBF process. The results revealed that hot cracking was closely linked to the thermal stress levels on the side or top surfaces of the as-built IN738LC specimens. The chessboard scanning strategy and substrate preheating promoted heat accumulation and reduced residual stress, thereby lowering the risk of cracking. These findings offer valuable insights into the relationship between residual stress and crack formation in LPBF-processed IN738LC alloys. •Residual stress distribution in LPBF IN738LC samples was detected by XRD and neutron diffraction.•A FEA model was developed to study temperature and thermal stress under different scan strategies.•The chessboard scanning strategy was favorable for heat accumulation and residual stress reduction.•Hot cracking was successfully inhibited by modifying the scan strategy and substrate preheating.