Aimed at the stress relaxation of giant size welding assembly of 5A06-H112 aluminum alloy cabinet, several welding processes were studied. The TIG and MIG welded joint microstructures were examined out. The ultimate strengths, residual stresses and the hardness of the TIG joint were measured in comparison with the MIG welding. The results showed that the residual stress of the joint in the welding assembly of aluminum alloy relaxes following the descending-after- rising curve. Due to the lower energy input and multi-layer welding process, TIG has the different ability to reduce the stress relaxation contrasted with MIG. The method which combines TIG with extending 8 to 10 aging days enables the stress relaxation weakens, and confines the assembly' s dimension stabilization finally.%针对生产现场大尺寸5A06-H112铝合金板箱形件拼焊制造过程中存在应力松弛的问题,对多种焊接工艺方法进行了研究.通过对不同焊接接头的力学性能试验、残余应力测试、焊接金相和硬度测量结果对比显示,铝合金焊接结构的应力变化存在先升后降的变化趋势,而TIG焊由于采用较小的线能量和多层焊,较MIG焊其应力松弛的程度存在差异.结果表明,增加焊后时效时间8～10d,并采用TIG焊技术将有效减小铝合金焊接结构的应力松弛,使端头下沉减少50％左右,满足了设计图纸的要求.
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