Effect of heat treatment on the microstructure and mechanical properties of laser melting deposition copper-containing antibacterial stainless steel

Heat treatment was conducted on copper-containing antibacterial stainless steel prepared by laser melting deposition (LMD) under three different strategies (Planar, serpentine, chessboard), and its effect on microstructure and mechanical properties was studied.. Solid solution treatment at 1050 °C-15 min and aging treatment at 800 °C-6 h/12 h were applied to achieve antibacterial properties in the steel. The results show that the LMD-based stainless steel specimens have an interlocking fish scale shape, with cellular crystals in the melt pool and columnar crystals with different growth directions at the boundaries. After heat treatment, the results show that the fish scale melt pool boundary gradually becomes shallower, and the grain transitions to equiaxed crystal. Moreover, the fracture surface after stretching exhibits uniform equiaxed dimples, indicating ductile fracture. LMDed specimens to have high strength but poor toughness. After solid solution treatment, the strength decreased by about 24 %, and the toughness increased by 25.98 %. After the aging treatment, the second phase strengthening effect of the copper-rich stage made the material stronger and higher. In short, after heat treatment, component segregation is eliminated, the structure is more uniform, and the overall performance of the material is improved.