Effect of Heat Treatment on Microstructure and Mechanical Behavior of Cu-Bearing 316L Stainless Steel Produced by Selective Laser Melting

Cu-bearing stainless steels (SSs) with high strength, excellent plasticity, and effective antimicrobial properties hold significant potential for applications in the marine industry. In this study, Cu-bearing SSs with copper ranging from 0 to 6.0 wt% were successfully prepared using selective laser melting (SLM) technology. For the Cu-bearing SSs with different copper contents, the effect of heat treatment on the microstructural and mechanical behaviors was studied systematically. Microstructural observations revealed that the subgrain size of Cu-bearing SSs increased with heat treatment at 500 °C and 700 °C for 6 h. Furthermore, the tensile strength and elongation increased after the heat treatment temperature due to the combined effect of dislocations, twins, and ε-Cu precipitated phases. Notably, after heat treatment at 700 °C, the SLM4.5Cu sample exhibited an abnormal rise in tensile strength and elongation. This finding suggests that the diffusion strengthening caused by ε-Cu precipitates exceeded the stacking fault energy. Consequently, the tensile strength and elongation reached 693.32 MPa and 56.94%, respectively. This work provides an efficient approach for preparing Cu-bearing SSs with exceptional strength and plasticity.