伸缩式搅拌头厚铝板搅拌摩擦焊缺陷及其补焊工艺

Friction-stir welded defects and repairing weld process of thick aluminum plates with telescopic stir-pin

采用伸缩式搅拌头对25 mm板厚2219-T6铝合金进行搅拌摩擦焊,在多道补焊时避免搅拌头轴肩的二次下压量造成的底部焊穿。对25 mm板厚2219-T6搅拌摩擦焊焊缝的微观组织、材料缺失型缺陷及弱连接型缺陷进行观察。结果表明:焊缝沿厚度方向分为轴肩影响区和搅拌针影响区,焊接参数的变化与这两区域中缺陷的产生存在一定关系,焊缝中的材料缺失型缺陷遵循一定的体积守恒关系。利用伸缩式搅拌头制备不同尺寸的焊缝根部未焊透缺陷,发现未焊透的深度与焊缝抗拉强度呈非线性关系。在统一的焊接参数规范下,调整搅拌针伸出长度进行多道焊,研究多道补焊工艺对焊缝组织性能的影响。

By using the telescopic stir-pin,25 mm-thickness 2219-T6 aluminum alloy couple plates were successfully friction-stir welded,and no plunge-through defect induced by the press amount of tool-shoulder was observed in the multi-pass repairing welding process.The microstructures in sound friction-stir welds,material-loss typed and weak-link typed weld defects were observed.The results show that the weld along the weld-thickness direction can be divided into shoulder-affected and pin-affected zones.The formation of defects is associated with the change of the welding parameters,and the inner material-loss typed defects follow volume conservation relationship.For the welds with different-size root flaws prepared by telescopic stir-pin,a non-linear relationship exists between the root-flaw depth and the weld tensile strength.In addition,under the unified welding parameters,by adjusting the telescopic pin length,the effects of multi-pass welding on the microstructure and properties of the resultant welds were investigated.