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通过将搅拌针向铝侧偏移0.3mm,对4mm厚的7075铝合金和AZ31B镁合金进行搅拌摩擦焊接,研究搅拌针偏移对镁铝合金焊接接头组织和性能的影响。组织分析表明:焊核区晶粒明显细化,呈现出片层状、条带状及旋涡状结构。XRD及EDS分析表明:与将搅拌针置于中心相比较,向铝侧偏移0.3mm所得接头中形成的Al12Mg17金属间化合物数量减少,但出现了Al3Mg2相。由于金属间化合物在接头热机械影响区附近大量出现,导致了该区域的硬度提高,但也成为接头的薄弱区,断裂发生于此。
The friction stir welding of 4mm thick 7075 aluminum alloy and AZ31B magnesium alloy was carried out by shifting the pin to the aluminum side by 0.3mm to study the effect of pin deflection on the microstructure and properties of the welded joint of magnesium aluminum alloy. Tissue analysis shows that the grain size in the weld nugget area is obviously refined, showing a lamellar, striped and swirling structure. The results of XRD and EDS showed that the amount of Al12Mg17 intermetallic compound formed in the joint obtained by 0.3 mm offset to the aluminum side was reduced as compared with that in the center of the stirring pin but the Al3Mg2 phase appeared. Intermetallic compounds appear in large numbers near the thermo-mechanical influence zone of the joint, resulting in an increase in the hardness of the zone but also as a weak zone of the joint where the fracture occurs.