(上海航天设备制造总厂有限公司，上海 200245)
摘 要: 采用带非圆截面搅拌针的焊接工具对5A06与2219铝合金进行了搅拌针下压的回填式摩擦点焊试验，对焊点进行微观组织结构分析与力学性能测试。结果表明：在焊接过程中，特殊的材料流动使得上板与下板的材料在焊点内部呈层状混合，并在焊点中心下部形成了上板材料留存区域。焊点完全消除了传统套筒下压带来的焊点竖直界面弱连接及环沟槽现象，但更容易在焊点下部形成延伸至焊核内部的界面残留，随着下压量的增加，进一步演变为向下板弯曲的Hook特征。拉剪试验表明，焊点断裂载荷随下压量增大而增加，最大拉剪力为5.7 kN；断裂模式为由焊点底部Hook缺陷起裂，穿过焊核区扩展断裂。
关键字: 回填式摩擦点焊；搅拌针下压；异种铝合金；显微组织；力学性能
（Shanghai Aerospace Equipments Manufacture Co., Ltd., Shanghai 200245, China）
Abstract:5A06/2219 aluminum alloy was pin plunge refill friction spot welded using non-circular cross section pin, the microstructure and tensile property of the joint were discussed. The results show that the special materials flow in welding spot makes upper and lower plates materials mixed in a multi-layer structure, and forms a residual area of upper plate material. The welding spot eliminates the weak-bonding of vertical interface in traditional sleeve plunge refill friction spot welding, but causes upper plate material of original lap interface extending into interior of stir zone, and as the plunge depth increases, makes it a characteristic of Hook defects. The tensile-shear tests show that the fracturing load of welding spots increases with the increase of plunge depth and the maximum tensile shear is 5.7 kN. It can be concluded that the cracks start with Hook defects and propagate into stir zone.
Key words: refill friction spot welding; pin plunge; dissimilar aluminum alloys; microstructure; mechanical property
