异种铝合金回填式搅拌摩擦点焊的组织与性能

Microstructure and mechanical properties of refill friction stir spot welded dissimilar 7075/6061 aluminum alloys

选用6061-T6与7075-T6铝合金为研究对象,研究异种合金回填式搅拌摩擦点焊接头的组织和拉剪性能.将7075铝合金作为上板,主要讨论套筒下扎深度对接头成形和性能的影响.结果表明,当套筒刚扎透上板时,接头内部无缺陷产生.随着套筒下扎深度的增大,接头内部会出现孔洞、撕裂和未充分回填等缺陷.当使用较小的套筒扎入量时,决定接头性能的关键位置,即钩状缺陷处和焊点中心搭接面处的结合情况良好.接头的断裂载荷随着套筒下扎深度的增大先增大后减小,最大载荷在深度为3.4 mm时达到7 236 N.

The microstructure and lap shear properties of refill friction stir spot welded dissimilar 7075/6061 aluminum alloys joints were studied. 7075 aluminum alloy was used as the upper sheet. The effect of sleeve plunge depth on joint formation and mechanical properties were discussed. The results showed that defect-free joints were obtained when plunge depth was small that the upper sheet was just penetrated. Defects such as void,tear and incomplete refilling appeared in the weld as the sleeve plunge depth increased. Hook and lap interface at joint center,which is critical to the mechanical properties of the joint,was well jointed when shoulder plunge depth was small. The fracturing load was firstly increased and then decreased with the increase of sleeve plunge depth. The maximum fracturing load was 7 236 N when using 3. 4 mm.