(1. 辽宁石油化工大学 机械学院，抚顺 113001；
2. 钢铁研究总院，北京 100081；
3. 北京科技大学 新材料技术研究院，北京 100083)
摘 要: 采用ER5356和ER5087两种焊丝对20 mm厚7A52铝合金进行冷金属过渡+脉冲焊接(CMT+P)，从焊接缺陷、晶粒尺寸及析出相等多方面研究Zr添加对焊接接头显微组织及力学性能的影响。结果表明：两种接头成形良好且均无明显缺陷，焊缝组织为铸态的等轴枝晶，并发现条状或块状的富铁杂质相AlFeMn以及黑色相Mg2Si。相比于ER5356焊丝，采用ER5087焊丝焊缝区的晶粒尺寸减小了28.7%，并存在圆形及椭圆形的纳米级强化相Al3Zr。两种接头均获得较高的抗拉强度，使用ER5356焊丝的接头强度约为293 MPa，达到母材强度的59.4%，而使用ER5087焊丝焊接接头的强度更高，约为316 MPa，焊接系数达到64.1%。两种接头的拉伸断裂位置均位于焊缝处，拉伸断口也均以韧窝为主并伴随明显的撕裂棱，表现为韧性断裂特征。
关键字: 7A52铝合金；CMT+P焊接；焊丝成分；显微组织；力学性能
（1. School of Machinery, Liaoning University of Petrochemical Technology, Fushun 113001, Chain;
2. Central Iron and Steel Research Institute, Beijing 100081, China;
3. Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, China）
Abstract:Cold metal transfer+pulse welding(CMT+P) of 20 mm thick 7A52 aluminum alloy was carried out with ER5356 and ER5087 welding wires. The effects of Zr addition on the microstructure and mechanical properties of welded joints were studied from the aspects of welding defects, grain size and precipitation. The results show that the two joints are well formed and have no obvious defects. The weld microstructure is as cast equiaxed dendrite, and strip or block iron rich impurity phase AlFeMn and black phase Mg2Si are found. Compared with ER5356 welding wire, the grain size of weld zone with ER5087 welding wire is reduced by 28.7%, and there are round and oval nano-sized strengthening phase Al3Zr. Both kinds of joints obtain high tensile strength. The joint strength using ER5356 welding wire is about 293 MPa, reaching 59.4% of the base metal strength, while the joint strength using ER5087 welding wire is higher, about 316 MPa, and the welding coefficient is 64.1%.The tensile fracture position of both joints is located at the weld, and the hardness here is also the lowest, indicating that the weld is the weakest area of the whole joint. The tensile fracture is mainly dimple with obvious tearing edge, which is characterized by ductile fracture.
Key words: 7A52 aluminum alloy; CMT+P welding; welding wire composition; microstructure; mechanical property
