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研究了大型车辆用７００５铝合金型材熔化极惰性气体保护焊（ＭＩＧ）焊接接头的显 微组织与力学性能，结果表明：７００５铝合金型材焊接接头最薄弱环节是焊道处．其次是焊接热影响 区内的软化区；焊道为通常的铸态组织，紧挨着焊道的是狭窄的半熔化区，随后通过热影响过渡到 基材区；焊接接头热影响区的硬度随停放时间的延长，硬度值显著提高，表现出明显的自然时效强 化效应。并对焊接接头不同区域的显微组织特征、性能变化及软化区形成的原因进行了分析和讨 论。
The microstructure and mechanical properties of 7005 aluminum alloy MIG welded joints for large vehicles were studied. The results show that the weakest link of 7005 aluminum alloy welded joints is weld bead. Followed by the softened zone within the weld heat affected zone (HAZ); the weld bead is the usual as-cast structure with a narrow semi-molten zone next to the weld bead, which then transitions to the base material zone by heat; the hardness of the HAZ of the welded joint With the extension of storage time, the hardness value increased significantly, showing a significant natural aging strengthening effect. The microstructure characteristics, performance changes and the reasons of softening zone formation in different regions of welded joints were analyzed and discussed.