热处理对SLM 316L不锈钢螺旋微丝微观组织和力学性能的影响

Effect of heat treatment on microstructure and mechanical properties of SLM 316L stainless steel spiral microwire

通过显微镜观察、拉伸试验和显微硬度试验分析了不同热处理参数对激光熔化(SLM)制成的螺旋微直径丝(SS316L-HMDW)的组织和力学性能的影响。结果表明:热处理后,SS316L-HMDW试样的微观组织发生明显变化,激光熔池消失,各向异性减小,力学性能提升;在不同保温时间下,SS316L-HMDW试样的晶粒尺寸随保温时间有不同程度地增加;随着热处理保温时间的增加,SS316L-HMDW试样的屈服极限和抗拉强度降低,伸长率增加,拉伸试样的断裂表面均为延性断裂,凹坑变大。经1200℃保温2 h热处理后,SS316L-HMDW试样的组织和力学性能均有显著变化,抗拉强度由585 MPa降低至398 MPa,屈服强度由40 MPa降低至25 MPa,伸长率明显增加至268%,试样的可塑性和韧性得到了增强。

Effects of different heat treatment parameters on the structure and mechanical properties of the spiral micro-diameter wire(SS316L-HMDW)made by laser melting(SLM)were analyzed through microscope observation,tensile test and microhardness test.The results show that after heat treatment,microstructure of the SS316L-HMDW specimen changes significantly,and the laser melt pool disappears,which reduces the anisotropy and contributes to the improvement of mechanical properties.Under different holding time,the grain size of the SS316L-HMDW specimen increases in different degrees with the holding time;with the increase of heat treatment holding time,the yield limit and tensile strength of the SS316L-HMDW specimen decreases,the elongation increases,and all of the fracture surfaces of tensile test specimens are ductile fracture,and the dimples become larger.After heat treatment at 1200℃for 2 h,the microstructure and mechanical properties of the SS316L-HMDW specimen change significantly.The tensile strength decreases from 585 MPa to 398 MPa,the yield strength decreases from 40 MPa to 25 MPa,and the elongation significantly increases to 268%.The plasticity and toughness of the specimens are enhanced.