异种铝合金回填式搅拌摩擦点焊缺陷及力学性能

采用回填式搅拌摩擦点焊技术对2 mm厚5052-H112与2024-T4铝合金进行了成功的连接.试验结果表明，当焊接工艺参数选择恰当时，可得到无缺陷接头；然而，焊接工艺窗口较窄，在高热输入条件下易产生多种缺陷，如粘连韧带、孔洞、裂纹、弱连接等，且这些缺陷主要分布在两板的结合面及焊具退出工件的退出线上；力学性能测试结果表明在低热输入条件下，接头的力学性能（一字拉伸与十字拉伸）最高，这与焊点在低热输入情况下组织缺陷较少有关；在一字和十字拉伸载荷作用下，接头的失效位置位于两板结合面及退出线上，在结合面处形成了有效的冶金连接.

Defects and mechanical properties of refill friction stir spot welded joint of dissimilar aluminum alloys

Dissimilar aluminum alloys of 5052-H112 and 2024-T4 (2 mm) were successfully joined by refill friction stir spot welding. Defects-free joint was obtained under optimum welding conditions. However, the welding parameters window was rather narrow. At the high heat input, lots of defects such as ligament bonding, voids, cracks and kissing bonding appear, which accumulated at the interface and the path in which the sleeve plunges into the workpiece. The mechanical properties tests show that the preferable strength is obtained under lower heat input welding conditions, which is consistent with that the defects-free joint tends to form under lower heat input welding conditions. The failure of the joint occurred at the interface and the path where the sleeve plunges into the workpiece both under tensile and cross-tension loadings. The effective metallurgical bonding formed at the interface.