选区激光熔化316L不锈钢的各向组织与性能

对采用选区激光熔化(SLM)制备的316L不锈钢增材制造试样进行了横向、纵向力学性能与微观组织分析。结果表明,增材制造SLM试件亚结构组织由尺寸为0.4 μm左右的胞状组织所构成,组织之间无明显的成分偏析,纵向与横向拉伸强度分别达到808和713 MPa,在经过1050 ℃热处理后,原组织中部分胞状组织消失,纵向及横向强度分别下降到673 MPa及579 MPa,增材制造试样相对传统热轧试样(550 MPa)具有明显的强度优势。SLM试样组织中存在未熔合缺陷,缺陷几何形状的方向性对其在拉应力作用下连接成裂纹有显著影响。热处理后缺陷长度方向与拉伸应力平行的纵向试样伸长率达到47.5%,横向试样伸长率为20%,伸长率指标均显著低于热轧316L钢试样,未熔合缺陷是导致3D打印试件塑性指标降低的主要因素之一。

Microstructure and properties of selective laser melted 316Lstainless steel in different directions

Microstructure and properties in transversal and longitudinal directions of 316L stainless steel additive manufacturing specimens produced by selective laser melting(SLM) were analyzed.The results show that the substructure of the SLM additive manufacturing specimens is composed of cellular microstructure with the size of 0.4 μm,and with no obvious composition segregation.Their transversal and longitudinal tensile strengths are 808 MPa and 713 MPa,respectively.After heat treatment at 1050 ℃,some of the cellular microstructures disappear,and the transversal and longitudinal strengths are reduced to 673 MPa and 579 MPa,respectively,which still have obvious strength advantages compared with the conventional hot rolled 316L steel(550 MPa).There are unfused defects in the SLM specimens,and the directivity and geometry of the defects have significant effect on the ability of the defects joining into a crack under the action of tensile stress.The elongation of the longitudinal specimen with defect length direction parallel to the tensile direction is 47.5%,and that of the transversal specimen is 20% after heat treatment.The elongation of the SLM specimen is significantly lower than that of the hot rolled 316L steel specimen.The unfused defect is one of the main factors leading to the decrease of plastic properties of the 316L stainless steel specimens processed by SLM.