Yanhou Liu

Selective laser melting (SLM)‐fabricated 316 L stainless steel often suffers from surface defects such as spheroidization, powder adhesion, and porosity, which deteriorate its mechanical and service performance. In this study, laser remelting was employed as a post‐treatment to modify the surface of SLM 316 L stainless steel. A single‐factor experimental design was adopted, in which the laser power was varied at 1050 W, 1150 W, and 1250 W, while the spot diameter (4 mm) and irradiation time (0.5 s) were kept constant. The effects of laser power on the microstructure, phase composition, residual stress, microhardness, and corrosion resistance of the remelted zone were systematically investigated. The results show that laser remelting significantly refines the surface microstructure. At 1150 W, the finest and most uniform equiaxed grains are obtained, with an average grain size of about 2–3 µ m. Energy-dispersive spectroscopy analysis reveals that after remelting, the relative Cr and Mn contents decrease by 1.24% and 0.02%, respectively, while Ni, Fe, and Mo increase by 0.73%, 0.51%, and 0.02%, respectively. X-ray diffraction (XRD) analysis indicates no phase transformation after remelting. Residual tensile stress is present on the remelted surface, which first increases and then decreases with increasing laser power. Microhardness is significantly enhanced; at 1150 W, the average hardness of the remelted zone reaches 276.43 HV, representing an increase of 37.21% over the original specimen. Electrochemical tests in 3.5% NaCl solution demonstrate that the corrosion resistance is substantially improved, with the best performance obtained at 1150 W, where the self‐corrosion potential is −0.263 V and the self‐corrosion current is 7.912 × 10 ⁻⁸ A. These findings confirm that laser remelting under optimized parameters can effectively enhance the surface properties of SLM 316 L stainless steel.