激光选区熔化304L不锈钢的工艺优化及组织性能研究

Study on Process Optimization and Microstructure and Mechanical Properties of Laser Selective Melting 304L Stainless Steel

为研究工艺参数对304L不锈钢激光选区熔化成形质量的影响,采用单因素试验法和正交试验法研究了激光功率、扫描间距及扫描速度对304L不锈钢相对致密度、硬度等的影响,得到了304L不锈钢的最佳工艺参数,并对成型试样进行了组织及力学性能表征。结果表明:激光功率为190 W、扫描间距为0.09 mm、扫描速度为800 mm/s时,试样硬度为75HRB,相对致密度为99.24%,成形质量最优;鱼鳞状组织均匀致密,气孔较少,熔池边界细小晶粒取向随机,熔池内部分粗大柱状晶有一定的择优性;其组织主要由奥氏体组成。试样的力学性能有明显的各向异性,拉伸断口有明显的颈缩,断裂形式为韧性断裂。

In order to study the influence of process parameters on the quality of 304L stainless steel by laser selective melting, the effects of laser power, scanning distance and scanning speed on the relative density and hardness of 304L stainless steel were studied by single factor experiment combined with orthogonal experiment method. The optimal process parameters of 304L stainless steel were obtained, and the microstructure and mechanical properties of the formed samples were characterized. The results show that when the laser power is 190 W, the scanning distance is 0.09 mm, and the scanning speed is 800 mm/s, the hardness of the sample is 75 HRB, the relative density is 99.24%, and the forming quality is the best. The scale-like microstructure is uniform and dense with few pores, the boundary of the molten pool is fine, and the grain orientation is basically random, and some of the coarse columnar crystals in the molten pool have a certain preference;the microstructure is mainly composed of austenite. The mechanical properties of the sample have obvious anisotropy, the tensile fracture has obvious necking, and the fracture form is ductile fracture.