铝合金多股复合焊丝脉冲MIG焊接接头组织与性能分析

选用铝合金多股复合焊丝对5A06板材进行脉冲MIG对接焊接，并与传统单丝TIG焊接接头的组织与性能进行对比.结果表明，采用铝合金多股复合焊丝脉冲MIG焊时，焊接接头的抗拉强度最大可达340 MPa （为母材强度的86.7%）.MIG焊接接头性能与TIG焊相比差异较小，但MIG焊可以提高焊接效率约4倍.焊接接头热影响区的软化主要受较高的热输入导致的晶粒尺寸增加、再结晶比例较大以及析出相的粗化和减少影响，而采用铝合金多股复合焊丝脉冲MIG焊能够降低焊接过程的热输入，细化晶粒，减弱MIG焊接接头中Mg元素的烧损和析出物的减少，达到控制焊接接头软化的目的.

Microstructure and mechanical properties of pulse MIG aluminum alloy welded joints by means of a novel multi-strands composite welding wire

In this study, a novel multi-strand composite welding wire was adopted in 5A06 aluminum pulse MIG welding method, and the microstructures and properties of aluminum alloy multi-strand composite wire welded joints were compared with those of traditional TIG welded joint. The results show that the welded joint used by this novel wire has a better tensile strength, which reaches up to 340 MPa (86.7% of the base metal). The performance of MIG welded joint is similar to that of TIG welded joint, and it can improve welding efficiency by about 4 times. It is also found that the softening of the heat affected zone of the welded joint is mainly affected by the larger grain size and the higher recrystallization ratio, the lower Mg content as well as the coarsening and reduction of the precipitated phase caused by higher heat input. In addition, the pulse MIG welding method with this novel wire can reduce the heat input in welding process, refine grains, and can significantly weaken the loss of Mg element and precipitation. Based on these advantages, the softening of the pulse MIG welded joint decreases and the excellent properties of welded joint can be obtained.