固溶及双时效处理对增材制造316L不锈钢组织性能的影响

Effect of solution and double aging treatment on microstructure and properties of 316L stainless steel prepared by selective laser melting

采用激光选区熔化技术制备了316L不锈钢,并对其进行了固溶及双时效处理,利用光学显微镜、X射线衍射仪、电子万能试验机和显微硬度仪等研究了316L不锈钢热处理后的组织和性能。结果表明:选区激光熔化成形的316L不锈钢试样的相邻熔池搭接紧密,搭接边界清晰,微观组织主要是生长方向各异的胞状晶;经固溶及双时效处理后,316L不锈钢的晶粒逐渐长大、熔池边界逐渐消失且边界缺陷逐渐减少,晶界处析出的M_(23)C_(6)导致其韧性有所降低,抗拉强度为638 MPa,屈服强度为592 MPa,伸长率为28.5%。XRD结果表明热处理没有改变316L不锈钢的元素含量且没有新相生成。

316L stainless steel was prepared by selective laser melting technology,and then solution and double aging treatment for it was carried out.Microstructure and properties of the 316L stainless steel after heat treatment were studied by means of optical microscopy,X-ray diffractometer,electronic universal testing machine and microhardness tester.The results show that the adjacent molten pool of the 316L stainless steel sample prepared by selective laser melting is closely overlapped,the overlapping boundary is clear,and the microstructure is mainly cellular crystals with different growth directions.After solution and double aging treatment,the grain of the 316L stainless steel gradually grows,the molten pool boundary gradually disappears and the boundary defects gradually decrease.Its toughness decreases due to the M_(23)C_(6)precipitated at the grain boundary,the tensile strength is 638 MPa,the yield strength is 592 MPa and the elongation is 28.5%.XRD results show that heat treatment does not change the element content of the 316L stainless steel and no new phase is formed.