大层厚下选区激光熔化成形316L不锈钢工艺的优化

Process Optimization of Selective Laser Melting Formed316L Stainless Steel under Large Layer Thickness

在铺粉厚度为0.15 mm的大层厚条件下采用选区激光熔化技术制备316L不锈钢试样,研究了激光功率(750~850 W)、扫描速度(800~1000 mm·s^(-1))、扫描间距(0.06~0.10 mm)对其相对密度、显微组织与性能的影响,对选区激光熔化工艺进行了优化。结果表明:随着激光功率、扫描速度或扫描间距的增大,大层厚下成形试样的相对密度都呈先增大再减小的变化趋势。当激光功率为800 W、扫描速度为900 mm·s^(-1)、扫描间距为0.08 mm时,成形试样的拉伸性能最优,其抗拉强度和断后伸长率分别为682.7 MPa和33.4%,与小层厚成形试样相近,此时的显微硬度为224.77 HV,显微组织由尺寸为0.4~1.0μm的等轴晶组成,在质量分数3.5%NaCl溶液中的自腐蚀电位达到-0.69 V,表现出最优的耐腐蚀性能。

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(800-1000 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 0.4-1.0μm;the free-corrosion potential in 3.5wt%NaCl solution reached-0.69 V,showing the best corrosion resistance.