Laser shock processing on selective laser melted 15-5PH stainless steel: Improving mechanical properties and wear resistance

Laser shock processing (LSP) is an effective mechanical surface hardening technology to refine the microstructure on the near-surface layer of material, thereby improving the mechanical properties, service lives, wear resistance, corrosion resistance and so on. In this work, the 15-5PH stainless steel experimental samples were fabricated by selective laser melting (SLM). Subsequently, a SIA-LSP-23 series LSP system with laser energy of 6 J, pulse width of 15 ns and spot diameter of 3 mm was applied to treat the surface of SLMed 15-5PH stainless steel experimental samples. Meanwhile, the mechanical properties, surface topography, microstructural evolution and wear behaviour of SLM 15-5PH stainless steel experimental samples prior and after LSP treatment were investigated. After the LSP treatment, the XRD diffraction peaks were shifted without any new phase formation. Since the severe plastic deformation, the surface roughness was increased. The tensile residual stress in near-surface layer was transformed to beneficial compressive residual stress. At the same time, the microhardness and the wear resistance of SLMed 15-5PH stainless steel were improved due to the refine effect of the microstructures induced by LSP.