激光增材制造316L不锈钢退火过程中微观组织演变和力学性能  

Microstructure evolution and mechanical properties of laser additive manufactured 316L stainless steel after annealing process

作　　者：郑磊 徐达 鲁宇杰 廖文超 殷安民[1,2] 陈候 Zheng Lei;Xu Da;Lu Yujie;Liao Wenchao;Yin Anmin;Chen Hou(School of Mechanical Engineering and Mechanics,Ningbo University,Ningbo Zhejiang 315211,China;Zhejiang Provincial Key Laboratory of Part Rolling Technology Research,Ningbo Zhejiang 315211,China)

机构地区：[1]宁波大学机械工程与力学学院,浙江宁波315211 [2]浙江省零件轧制成形技术研究重点实验室,浙江宁波315211

出　　处：《金属热处理》2024年第4期66-77,共12页Heat Treatment of Metals

基　　金：宁波市重点研发计划(2023Z012);南京大学固体微结构物理国家重点实验室开放基金(M36043)。

摘　　要：利用扫描电镜(SEM)、电子背散射衍射(EBSD)、拉伸试验机研究了激光增材制造316 L不锈钢退火过程中的微观组织演变和力学性能。结果表明:在700℃退火后,鱼鳞状熔池形貌开始随着温度的升高逐渐转变为不规则长条状形貌,在750℃退火后,熔池内胞状和长条柱状亚结构转变为球形亚结构组织和三角形的点状凹坑形组织。随着退火温度的升高,晶粒尺寸先减小后增大,位错密度重新排序,胞状亚结构的溶解,亚结构组织,变形组织和大小角度晶界的演变反映着位错密度的降低,导致强度的下降和塑性的增强。在600℃×120 min退火时屈服强度为484.2 MPa,抗拉强度为665.6 MPa,伸长率为47.7%,在850℃×120 min退火时屈服强度为410.4 MPa,抗拉强度为639.1 MPa,伸长率为59.7%;随着保温时间的延长,变形组织转变为亚结构组织;在650℃温度下保温时间由30 min增加到120 min时,亚结构组织由24.1%增多到82.3%;在850℃温度下保温时间由30 min增加到120 min时,亚结构组织由24.9%增多到59.2%。The microstructure evolution and mechanical properties of laser additive manufactured 316L stainless steel after annealing process were studied by means of scanning electron microscope(SEM),electron backscatter diffraction(EBSD)and tensile testing machine.The results show that after annealing at 700℃,the morphology of the fish⁃scale molten pool begins to gradually transform into an irregular strip shape as the temperature increases.After annealing at 750℃,the cellular and long columnar substructures in the molten pool transform into spherical substructure and triangular point⁃like pit⁃shaped microstructure.As the annealing temperature increases,the grain size first decreases and then increases,the dislocation density is reordered,the cellular substructure is dissolved,and the evolution of the substructure and large and small angle grain boundaries reflects the decrease in dislocation density,leading to decrease in strength and enhancement in plasticity.When the annealing at 600℃for 120 min,the yield strength is 484.2 MPa,the tensile strength is 665.6 MPa,and the elongation is 47.7%.When annealing at 850℃for 120 min,the yield strength is 410.4 MPa,the tensile strength is 639.1 MPa,and the elongation is 59.7%.As the holding time increases,the deformation zone transforms into substructure;when the holding time is increased from 30 min to 120 min at temperature of 650℃,the substructure increases from 24.1%to 82.3%;when the holding time is increased from 30 min to 120 min at temperature of 850℃,the substructure is increased from 24.9%to 59.2%.

关 键 词：激光增材制造 316L不锈钢 退火处理 微观组织 力学性能 

分 类 号：TG156[金属学及工艺—热处理]