Weldability of Additively Manufactured Austenitic Stainless Steels

Additive manufacturing (AM) can enable faster, lower-cost production of power generation components. However, implementation of AM parts into service requires welding to other components, and the weldability of AM alloys is not well characterized. On-cooling hot ductility testing was performed between 1000°C and 1300°C on gas metal arc directed energy deposition (GMADED), laser powder bed fusion (L-PBF), and wrought 316-series stainless steels to evaluate weldability and ductility dip cracking (DDC) susceptibility of AM austenitic stainless steels. The results were analyzed with respect to variations in dynamic recrystallization, absorbed energy, and fracture mechanism. Single and multipass autogenous gas tungsten arc welds were performed on GMADED, L-PBF, and wrought plates to correlate hot ductility behavior with DDC susceptibility in welded specimens. GMA-DED 316(L/H/LSi) exhibited good hot ductility regardless of post-build heat treatment, while L-PBF 316L exhibited reduced ductility across all conditions. L-PBF 316L also exhibited lower absorbed energy, which correlated with reduced hot ductility and intergranular fracture, whereas the GMA-DED and wrought conditions exhibited greater absorbed energy and ductile fracture. The reduced weldability of L-PBF 316L is suggested to be associated with grain boundary embrittlement from impurity elements segregation during primary austenite solidification. Heat-affected zone microcracking was observed in the GTAW welds of L-PBF 316L, confirming susceptibility to DDC and supporting the correlation between reduced hot ductility and weldability issues.