(湖南大学 汽车车身先进设计制造国家重点实验室，长沙 410082)
摘 要: 采用光纤激光器对1.4 mm厚DC51D+ZF镀锌钢和1.2 mm厚6016铝合金平板试件进行添加Mn、Zr粉末的激光搭接焊试验，利用金相显微镜、显微硬度仪、扫描电镜、X射线衍射仪、微机控制电子万能试验机等研究焊接接头各区域的金相组织、显微硬度、断口形貌、主要物相与接头的力学性能。结果表明：在钢/铝激光焊中添加Mn、Zr粉末，焊接接头平均抗剪强度与没有添加粉末相比，有所提高，其中添加Zr粉末的提高效果明显；Mn、Zr粉末的添加改变了钢/铝界面的元素分布、物相组成及微观组织形态，添加Mn能提高熔池金属的流动性，利于钢/铝界面结合，而添加Zr，焊缝区晶粒细小，形成新的ZrFe3.3Al1.3韧性相，抑制Fe-Al脆性金属间化合物生成。因此，添加Mn、Zr均改善了钢/铝焊接接头的力学性能。
关键字: 激光焊接；异种金属；金属间化合物；微观组织；力学性能
（State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body,
Hunan University, Changsha 410082, China）
Abstract:The fiber laser welding test with Mn and Zr powder addition was carried out on the DC51D+ ZF galvanized steel with thickness of 1.4 mm and the 6016 aluminum alloy with thickness of 1.2 mm. By using optical microscopy, electron microscopic hardness, scanning electron microscopy, X-ray diffraction and the tensile test, the microstructure, hardness, mechanical properties of joints, fracture morphology and the main phase of the welded joint region were studied. The results indicate that when Mn, Zr powders are added in steel/aluminum, the average shear strength of the welding sample is improved compared with that without power addition, and Zr is considered as the best power based on improved mechanical properties of joints. The element distribution, phase composition and microstructure of the steel/aluminum interface are changed due to Mn and Zr powders addition. When Mn powder is added in steel/aluminum, the fluidity of the molten pool metal is improved, which promotes the combination of the steel/aluminum interface, when Zr powder is added in steel/aluminum, fine grain is seen, and a new ductile intermetallic compound ZrFe3.3Al1.3 inhibits the generation of intermetallic compounds of Fe-Al, which can improve the mechanical properties of weld metal with Mn and Zr powder addition.
Key words: laser welding; dissimilar metal; intermetallic compound; microstructure; mechanical properties
