316L不锈钢激光瞬时退火软化工艺研究  

Laser Annealing and Softening Process of 316L Stainless Steel

作　　者：蒋可静 王梁 张群莉 胡勇 姚建华 刘蓉 JIANG Ke-jing;WANG Liang;ZHANG Qun-li;HU Yong;YAO Jian-hua;LIU Rong(Institute of Laser Advanced Manufacturing Zhejiang University of Technology,Hangzhou 310023;College of Mechanical Engineering,Zhejiang University of Technology,Hangzhou 310023,China;Department of Mechanical and Aerospace Engineering,Carleton University,Ottawa KIS 5B6,Canada)

机构地区：[1]浙江工业大学激光先进制造研究院,杭州310023 [2]浙江工业大学机械工程学院,杭州310023 [3]卡尔顿大学机械和航空工程系

出　　处：《表面技术》2019年第2期10-16,共7页Surface Technology

基　　金：浙江省公益技术应用研究项目(2017C31048)~~

摘　　要：目的解决冲压中加工硬化导致的高强度低塑性的问题。方法提出以矩形光斑的温控模式激光为热源,对工件进行选区瞬时退火,达到局部软化的目的。通过金相显微分析、显微硬度分析、力学拉伸及断口分析,分别评价激光瞬时退火软化后试样显微组织、显微硬度、抗拉强度、断后伸长率和断口形貌。结果金相组织显示,不同工艺条件下的晶粒大致呈现变形晶粒、再结晶晶粒、细小晶粒和较大等轴晶4种状态。由显微硬度可知,固溶态母材硬度为173HV0.2,加工硬化后达到341HV0.2。当激光温控温度为1400℃,扫描速度分别为5、10、15 mm/s时,软化处理后硬度分别为164、173、257HV0.2。而扫描速度一定时,激光温控温度越高,软化处理后硬度越低。对试样做室温拉伸试验发现,激光瞬时退火后强度降低,塑性提高。当温控温度为1400℃,扫描速度为5 mm/s时,抗拉强度由加工硬化后的911 MPa下降到591 MPa,接近固溶态母材的570 MPa,断后伸长率由18.2%恢复到54.7%,达到固溶态母材的95.5%。结论激光瞬时退火软化可有效降低加工硬化后的材料强度,提高材料塑性,使其恢复大变形能力。其软化程度随激光温控温度的降低、激光扫描速度的提高而降低,在较优工艺参数下,激光瞬时软化后性能甚至优于母材性能。The work aims to solve the problem of excessive strength and low plasticity caused by hardening in stamping. The temperature-controlled mode laser with a rectangular spot was used as the heat source. The workpiece was subjected to instantaneous annealing in the selected area to achieve local softening. The metallographic microscopic analysis, microhardness analysis, mechanical tensile analysis and fracture analysis were taken to evaluate the microstructure, microhardness, tensile strength, elongation after fracture and fracture morphology of samples after laser annealing and softening. The metallographic structure analysis showed that the grains exhibited deformed grains, recrystallized grains, fine grains and large equiaxed crystalsunder different annealing parameters. From the microhardness results, the hardness of the solid solution base material was 173 HV0.2, but reached 341 HV0.2 after hardening. When the laser control temperature was 1400 ℃ and the scanning speed was 5, 10, and 15 mm/s, the hardness after softening was 164 HV0.2, 173 HV0.2, and 257 HV0.2, respectively. When the scanning speed was constant, the higher the laser control temperature was, the lower the hardness after softening was. From the tensile test, the strength of the sample was reduced after the instantaneous laser annealing but the plasticity was improved. When the temperature control temperature was 1400 ℃ and the scanning speed was 5 mm/s, the tensile strength decreased from 911 MPa to 591 MPa after hardening, which was close to 570 MPa of the solid solution parent metal, and the elongation after fracture was restored from 18.2% to 54.7% which reached 95.5% of the solid solution base metal. Laser instantaneous annealing and softening can effectively reduce the material strength after hardening, improve the plasticity of the material, and restore the strong deformation ability. The softening degree decreases with the decrease of the laser temperature control temperature and the increase of laser scanning speed. Under the optimal l

关 键 词：316L不锈钢 激光热处理 选区退火软化 晶粒形貌 强度与塑性 

分 类 号：TG156[金属学及工艺—热处理]