The effect of repair welding on the microstructure and mechanical properties of the welded joint was investigated. The results show that the difference of microstructure in different locations of the original welded joint (OWJ) is mainly related to the production process. The AT5 side is an extruded profile, exhibiting equiaxed grain characteristics, while the AT4 side is a rolled sheet, displaying flat long grain. The grain boundary orientation difference in different positions of repair welded joint (RWJ) is various from that of OWJ, especially the change of proportion of small angle grain boundary in AT4-HAZ II is large. The tensile strength of the OWJ and RWJ are 283 MPa and 280 MPa, respectively, and the corresponding welded joint coefficients are 78.6 % and 77.8 %, respectively, which can fulfill the demands of practical engineering applications. Due to the existence of pores and inclusions, the crack of OWJ originates in the junction of HAZ I near the 7N01-T4 side, then expands along the welded zone, while the RWJ fails in the junction of the original weld and the weld passes.

研究了补焊对焊接接头组织和力学性能的影响。结果表明，原始焊接接头（OWJ）不同位置的显微组织差异主要与生产过程有关。AT5侧面是挤压型材，具有等轴晶粒特性，而AT4侧面是压延板，具有扁平的长晶粒。修复焊缝（RWJ）不同位置的晶界取向差异与OWJ不同，尤其是AT4-HAZ II中小角度晶界的比例变化较大。OWJ和RWJ的抗拉强度分别为283 MPa和280 MPa，相应的焊接接头系数分别为78.6％和77.8％，可以满足实际工程应用的需求。由于存在气孔和夹杂物，OWJ的裂纹起源于靠近7N01-T4侧的HAZ I的交汇处，然后沿焊接区域扩展，而RWJ则在原始焊缝的交汇处失效，并且焊缝通过。