纳秒脉冲激光清洗对AZ31B镁合金激光焊接质量的影响  

Influence of Nanosecond Pulsed Laser Cleaning on Laser Welding Quality of AZ31B Magnesium Alloy

作　　者：张明军[1] 李雄 李河清[1] 李晨希 张健[1] 程波 王开明 毛聪[1] 胡永乐[1] Zhang Mingjun;Li Xiong;Li Heqing;Li Chenxi;Zhang Jian;Cheng Bo;Wang Kaiming;Mao Cong;Hu Yongle(Hunan Provincial Key Laboratory of Key Technologies for High-performance Intelligent Manufacturing of Mechanical Equipment of College of Automotive and Mechanical Engineering,Changsha University of Science and Technology,Changsha 410114)

机构地区：[1]长沙理工大学,汽车与机械工程学院机械装备高性能智能制造关键技术湖南省重点实验室,长沙410114

出　　处：《汽车工程》2022年第11期1786-1796,共11页Automotive Engineering

基　　金：国家自然科学基金(51875050);湖南省教育厅科学研究项目(20B008);长沙市自然科学基金(kq2014101,kq2202197);长沙市重点研发计划项目(kh2201275)资助。

摘　　要：为提高AZ31B镁合金激光焊接质量,采用纳秒脉冲激光清洗对试件表面进行焊前清洗。采用扫描电镜和能谱仪分析了不同清洗方式下的表面形貌和化学成分,通过高速摄影直接观测了激光焊接动态过程,研究了不同清洗方式和参数对表面清洗效果和焊接质量的影响。结果表明,纳秒脉冲激光清洗可有效去除镁合金表面的氧化膜,且试件表面呈现细密的微结构特征。与未处理和钢刷打磨处理相比,焊前激光清洗对镁合金激光焊接小孔和熔池的稳定具有积极作用;焊缝表面鱼鳞纹均匀细小,接头显微组织沿板厚方向分布均匀,气孔和裂纹等缺陷少。焊前激光清洗可显著提升镁合金激光焊接接头伸长率。与未处理和钢刷打磨处理相比,接头伸长率分别提高50.3%和16.4%。合适的激光清洗可有效清除镁合金表面氧化膜,改善表面微结构,得到较高的接头抗拉强度和伸长率。In order to enhance the laser welding quality of AZ31B magnesium alloy,the surfaces of specimen are cleaned by nanosecond pulsed laser before welding. The surface morphologies and chemical compositions with different ways of cleaning are analyzed by scanning electron microscope and energy spectrometer. The dynamic processes of laser welding are observed via high-speed photography to analyze the effects of the different ways of cleaning and parameters on the surface cleaning effect and welding quality. The results show that the oxide film on magnesium alloy surface can be effectively removed by nanosecond pulsed laser cleaning,with the surface of specimen exhibiting fine microstructure features. Compared with the untreated or steel-brushed processes,laser cleaning process has a positive effect on the stabilities of the keyhole and molten pool during laser welding of magnesium alloy:the scale-like ripples on weld surface are uniform and fine,the microstructure of the joint is evenly distributed along the direction of plate thickness,with few defects of pores and cracks. Furthermore,the pre-weld laser cleaning can significantly increase the elongation rate of the laser weld joint of magnesium alloy. Compared with the untreated or steel-brushed processes,its joint elongation increases by 50.3% and 16.4% respectively. Appropriate laser cleaning can effectively remove the oxide film on the magnesium alloy surface,improve the surface microstructure,and obtain a higher tensile strength and elongation rate of the weld joints.

关 键 词：AZ31B镁合金 激光焊接 激光清洗 力学性能 

分 类 号：TG456.7[金属学及工艺—焊接]