Influence of Heat Treatment on Stainless Steel 316L Alloy Manufactured by Hybrid Additive Manufacturing Using Powder Bed Fusion and Directed Energy Deposition

The present study investigated the effect of heat-treatment on the Stainless Steel 316L (SS316L) hybrid sample fabricated by using Directed Energy Deposition (DED) and Powder Bed Fusion (PBF) Additive Manufacturing (AM) process. The relationship between the microstructure and mechanical properties of the additively manufactured hybrid sample is studied. Further, the additively manufactured SS316L hybrid sample is subjected to different heat treatment conditions namely, stress relief, solution annealing and hot isostatic pressing and the changes happening in the mechanical and metallurgical characteristics of the hybrid sample is studied post heat treatment. From the investigation it is found that the DED process can be effectively used for depositing SS316L structure over the PBF built SS316L substrate. In addition, the mechanical characteristics of the additively manufactured SS316L hybrid sample can be effectively modified through heat treatment. As built SS316L hybrid sample has microhardness of 230.5 HV, ultimate tensile strength of 733 MPa, the yield strength value of 512 MPa. The solution treatment (HT2) of hybrid sample improves the ductility and leads to highest total elongation of 70.1%.