采用光纤激光-CMT复合焊接工艺对6 mm厚5454-H24/6106-T6铝合金型材进行对接焊试验。经工艺参数优化后, 得到成形良好的焊接接头,在此基础上分别进行了1次、2次和3次补焊, 对比分析了多次补焊后接头的显微组织和力学性能, 并评估了接头的热裂纹敏感性。结果表明, 所得到对接接头和3次补焊接头的焊缝横截面均为典型的“Y”型, 随着补焊次数增多, 熔宽增大, 相应的热影响区(Heat affected zone, HAZ)范围也越宽, 焊缝区显微组织晶粒变大, 气孔倾向有所增加。复合焊接接头的抗拉强度和屈服强度都有所降低, 焊接接头均于焊缝处断裂。补焊后, 6106侧热影响区显微硬度有所下降, 而5454侧热影响区未出现明显降低。补焊后, 热裂纹敏感性升高, 在控制好工艺和降低焊接缺陷的情况下, 可以进行三次补焊。

The butt welding test was carried out on the 6 mm thick 5454-H24 /6106-T6 aluminum alloy sections by fiber laser-CMT hybrid welding processes. After the optimization of the process parameters, the well-formed welding joints were obtained. On this basis, the 1, 2 and 3 repair welding were performed respectively. The microstructure and mechanical properties of the joints after multiple repairs were analyzed, and the thermal crack sensitivity of the joints was evaluated. The results show that the weld cross section of the obtained butt joint and the three repairs joints are both typical "Y" type. As the number of repair welding increases, the weld width increases, and the corresponding heat affected zone (HAZ) range is wider. The microstructure of the weld zone is enlarged and the tendency of the pores is increased. The tensile strength and yield strength of the hybrid welded joint are reduced, and the welded joint is broken at the weld. After repair welding, the microhardness of the heat affected zone on the 6106 side decreased, while no obvious decrease occurred in the heat affected zone on the 5454 side. After the repair welding, the thermal crack sensitivity increases. Three repair welds can be carried out under the condition that the process is well controlled and the welding defects are reduced.