Process Optimization of Selective Laser Melting Formed 316L Stainless Steel under Large Layer Thickness

316L stainless steel samples were prepared by selective laser melting under the condition of large layer thickness with powder thickness of 0.15 mm. The effects of laser power (750-850 W), scanning speed (800-1 000 mm·s^-1) and scanning spacing (0.06-0.10 mm) on the relative density, microstructure and properties of 316L stainless steel were studied, and the selective laser melting process was optimized. The results show that with the increase of laser power, scanning speed or scanning spacing, the relative density of the formed samples with large layer thickness all increased first and then decreased. When the laser power was 800 W, the scanning speed was 900 mm · s^-1, and the scanning spacing was 0.08 mm, the tensile properties of the formed sample were the best, and the tensile strength and the percentage elongation after fracture were 682.7 MPa and 33.4%, respectively, which were close to those of the small layer thickness formed sample. Meanwhile, the microhardness was 224.77 HV, and the microstructure was composed of equiaxed grains with size of 0.4-1.0 μm; the free-corrosion potential in 3.5wt% NaCl solution reached -0.69 V, showing the best corrosion resistance.