激光选区熔化316L不锈钢的表面形貌和硬度研究

Study on Surface Morphology and Hardness of 316L Stainless Steel by Laser Selective Melting

采用激光选区熔化(SLM)制备了不同激光能量密度的316L不锈钢块状试样,利用光学显微镜(OM)和硬度仪等观察和分析316L不锈钢的显微组织与硬度。结果表明:扫描速度大于激光功率对单道熔池宽度的影响,其中,当激光功率固定时,速度越大,熔池宽度越小;当扫描速度固定值时,激光功率越高,熔池宽度越大。随着体激光能量密度增加,相邻的熔道及上下成型层能够较好搭接,熔池形态均匀稳定,空隙和微孔等缺陷逐渐消除,同时熔池断续减少,熔池宽度逐渐由小变大,其具体值从40.19μm增加到108.34μm,不同方向的维氏硬度逐渐增大,其中体激光能量密度在110~120 J·mm-3时,xoy、xoz、yoz面显微硬度达到最优。此外,激光选区熔化成型316L不锈钢的硬度存在明显的各向异性。

Laser selective melting technology(SLM)was used to prepare 316 L stainless steel bulk specimens with different energy densities.The microstructure and hardness of 316 L stainless steel were observed and analyzed using optical microscope(OM),scanning electron microscope(SEM)and hardness tester.The results show that the scanning speed has greater influence on the width of the single-pass molten pool than laser power.Among them,when the laser power is fixed,the greater the speed,the smaller the width of the molten pool.When the scanning speed is fixed,the higher the laser power,the greater the width of the molten pool.As the volume laser energy density increases,the adjacent melting channels and the upper and lower forming layers can overlap well,the shape of the molten pool is uniform and stable,and defects such as voids and micropores are gradually eliminated.At the same time,the molten pool is reduced intermittently,and the width of the molten pool is gradually changed.From small to large,the specific value increases from 40.19μm to 108.34μm,and the Vickers hardness in different directions gradually increases.When the volume laser energy density is 110~120 J·mm-3,the microhardness of the xoy,xoz,and yoz surfaces is optimal.In addition,the hardness of 316 L stainless steel by laser selective melting has obvious anisotropy.