微米级选区激光熔化316L不锈钢的拉伸力学性能  

Tensile Mechanical Properties of Micro-Selective Laser Melted 316L Stainless Steel

作　　者：张楠 张海武 王淼辉 ZHANG Nan;ZHANG Haiwu;WANG Miaohui(China Machinery Institute of Advanced Materials Co.Ltd.,Zhengzhou 450001,China;China Academy of Mechanical Science and Technology Group Co.Ltd.,Beijing 100044,China)

机构地区：[1]中机新材料研究院(郑州)有限公司,郑州450001 [2]中国机械科学研究总院集团有限公司,北京100044

出　　处：《金属学报》2024年第2期211-219,共9页Acta Metallurgica Sinica

基　　金：国家自然科学基金项目No.51975240;北京市自然科学基金项目No.2222093;中国机械科学研究总院集团技术发展基金项目No.812201Q9。

摘　　要：为辅助理解金属材料高精密增材制造成形机理,本工作利用微米级选区激光熔化(micro-selective laser melting,M-SLM)技术制备了316L不锈钢,对其拉伸性能及断裂行为进行了研究,并对断后横向和纵向拉伸试样显微组织和断口形貌进行了表征与分析,对近断面塑性变形区的晶粒取向、晶界特征分布等进行了电子背散射衍射(EBSD)分析。结果表明:M-SLM制备316L不锈钢晶粒内部存在尺寸为100~300 nm的胞状组织结构,拉伸断口呈韧窝状,窝口直径80~500 nm,这使得316L不锈钢的横向平均抗拉强度达692.1 MPa,纵向平均断后延伸率达54.6%,明显优于传统SLM技术制备的316L不锈钢。M-SLM制备316L不锈钢在拉伸过程中奥氏体Σ3孪晶界的出现与晶粒取向有关,其在取向接近<111>的晶粒中较易出现。进一步分析指出,Σ3晶界的出现阻断了特殊晶界网络的连通性。通过基于EBSD的矩形截面法对共格Σ3(Σ3_(c))和非共格Σ3(Σ3_(ic))晶界进行了统计分析,显示316L横向拉伸试样近断口区的Σ3_(c)和Σ3_(ic)晶界数量百分比分别约为43%和57%,而纵向拉伸试样近断口区的Σ3_(c)晶界数量百分比提高至约70%。Σ3_(c)孪晶界的增加使得总晶界能降低,是导致M-SLM制备316L不锈钢纵向拉伸强度普遍低于横向拉伸强度的原因。Compared with selective laser melting(SLM),the micro-SLM(M-SLM)technology offers the advantages of small spot diameter(<20μm),high forming precision(20-50μm),and surface roughness(Ra)of up 1μm,which implies that the M-SLM technology provides great potential for promotion and application in communication electronics,biomedical,and other fields in the future.In this work,316L stainless steel was prepared using M-SLM,and its tensile properties and fracture behavior were studied.The microstructures of transverse and longitudinal tensile specimens were also investigated.In addition,the fracture morphology was characterized and analyzed,and the grain orientation and grain-boundarycharacteristic distribution in the near-section plastic-deformation zone were further analyzed using electron backscatter diffraction(EBSD).The results showed that the 316L stainless steel prepared by M-SLM had a cellular structure with a size of 100-300 nm inside the grains.The tensile fracture was dimpleshaped,and the average dimple diameter was 80-500 nm,which allowed the transverse average tensile strength of the 316L stainless steel to reach 692.1 MPa,the longitudinal average elongation after fracture was 54.6%,which were obviously better than that of the 316L stainless steel prepared using traditional SLM.The appearance of austeniteΣ3 twin boundaries in the stretching process of the 316L stainless steel prepared by M-SLM was related to the grain orientation,which could more likely appear in grains with an orientation close to<111>.Further analysis indicated that the appearance ofΣ3 grain boundaries blocked the connectivity of the special grain-boundary network.Statistical analysis of the coherentΣ3(Σ3_(c))and incoherentΣ3(Σ3_(ic))grain boundaries using the EBSD-based rectangular-section method revealed that the amount percentages ofΣ3_(c) andΣ3_(ic) in the near-fracture region of the 316L transverse tensile specimen were approximately 43%and 57%,respectively.Meanwhile,the amount percentage ofΣ3_(c) in the same region of the 3

关 键 词：微米级选区激光熔化 316L不锈钢 拉伸性能 Σ3晶界 孪晶 

分 类 号：TG142[一般工业技术—材料科学与工程]