Effect of Heat Treatment on Microstructures and Mechanical Behaviors of 316L Stainless Steels Synthesized by Selective Laser Melting

In this work, 316L austenite stainless steels were fabricated by the selective laser melting (SLM) technique, and the as-printed samples were then treated by using two various routines, namely the intercritical annealing (IA) and the deep cryogenic treatment (DCT), respectively. Microstructural characterization, nanoindentation creep tests as well as tensile experiments were also performed on the achieved specimens to evaluate the effect brought by the various heat treatment routines. It is found that DCT treatment produces a finer microstructure with higher quantity of homogenous tiny precipitates, compared with the as-printed SLM and single IA counterparts. Such microstructure of the DCT specimen leads to a desirable indentation creep resistance at room temperature as well as a good mechanical performance on tension. In addition, applying a prior deep cryogenic treatment before the intercritical annealing brings more positive effects on the mechanical properties than only using IA. The result indicates that the DCT routine is definitely considerably beneficial for fabricating reliable metallic products fabricated by selective laser melting, and it provides an efficient alternative in real manufactures as well.