补焊次数对A6N01S-T5铝合金对接接头微观组织与力学性能的影响

Influence of repair welding times on microstructure and mechanical properties of A6N01S-T5 aluminium alloy

对A6N01S-T5铝合金进行一次焊接和三次补焊试验,系统分析补焊次数对接头微观组织和力学性能的影响。结果表明,焊缝区由α-Al以及(α-Al+Mg_2Si)的伪共晶组织构成;随着补焊次数的增加,焊缝区组织变化不大,热影响区产生过时效现象形成软化区。焊缝区显微硬度高于热影响区,且随补焊次数的增加热影响区范围增大,显微硬度值下降;这主要与热影响区过时效现象加剧有关。补焊对焊接接头抗拉强度和弯曲性能影响较小,而对延伸率影响较大;随着补焊次数的增加,延伸率不断下降。拉伸试样均断裂于热影响区,为接头力学性能的薄弱部分。

A original welding and three times repair welding were carried out in this paper,and the influences of repair welding time on microstructures and mechanical properties were studied systematically. The results show that the microstructure of weld zone mainly consists of primary α-Al and（α-Al＋Mg_2Si） pseudoeutectic;repair welding has little influence on the microstructure of weld zone,but further deteriorates the overaging in HAZ zone in which a soft zone is generated. The microhardness of weld zone is higher than that of HAZ zone; increasing repair welding times enlarges the range of HAZ zone,and decreases the microhardness meanwhile.This is mainly attributed to the overaging in HAZ zone. Repair welding time slightly affects on mechanical and bending properties of weld joints,but decreases the enlongation significantly with increasing repair welding times. The fracture occurs in the HAZ zone for all tensile samples,which is the weakest part in weld joints.