热处理对激光选区熔化成形316L不锈钢组织和力学性能的影响

Effect of heat treatment on microstructure and mechanical properties of 316L stainless steel prepared by selective laser melting

采用激光选区熔化成形工艺制备了316L不锈钢试样,并对其分别进行了400℃×4 h的退火处理以及1020℃×0.5 h的固溶处理。采用扫描电镜、显微硬度计及电子万能试验机等研究了直接成形态、退火态和固溶态试样的微观组织、拉伸性能、布氏硬度和夏比冲击吸收能量。结果表明:直接成形态试样经400℃×4 h退火后,组织变化不明显,抗拉强度、伸长率、布氏硬度及夏比冲击吸收能量都略有提高;直接成形态经1020℃×0.5 h固溶处理后,熔池搭接边界发生溶解,层层搭接边界消失,抗拉强度、屈服强度、布氏硬度分别降低了8.8%、27.2%、13.7%,伸长率、夏比冲击吸收能量分别提高了43%和25%。与其它两种状态相比,固溶状态下,试样的性能更稳定,强度与韧性的组合较好。

316 L stainless steel samples were prepared by selective laser melting(SLM) forming process and then were treated with annealing at 400 ℃ for 4 h, and solid solution treatment at 1020 ℃ for 0.5 h, respectively. Microstructure, tensile properties, Brinell hardness and Charpy impact absorbed energy of the SLM prepared, annealed and solid solution samples were studied by means of scanning electron microscopy(SEM), microhardness tester and electron universal testing machine. The results show that the microstructure changes of the SLM prepared sample after annealing at 400 ℃ for 4 h are not obvious, and the tensile strength, elongation, Brinell hardness and Charpy impact absorbed energy increase slightly. The lap boundaries of molten pool of the SLM prepared sample after solid solution treatment at 1020 ℃ for 0.5 h dissolve, the layer upon layer lap boundaries disappear, the tensile strength, yield strength and Brinell hardness decrease by 8.8%, 27.2% and 13.7%, respectively, and the elongation and Charpy impact absorbed energy increase by 43% and 25% respectively. Compared with the other two states, the properties of the SLM prepared sample after solid solution treatment at 1020 ℃ for 0.5 h are more stable, and the match of strength and toughness is better.