A stepped-shoulder friction stir welding tool containing a protruding inner shoulder and an outer shoulder was proposed to join AA2195-T8 Al-Cu-Li and AA2219-T6 Al-Cu alloys. The inner shoulder with a considerable plunge depth enhanced forging effect, and the outer shoulder with a low plunge depth prevented plasticized materials from overflowing out of welds, while the pin with milling facet promoted material flow. The sound joint with a weld thinning of 0.05 mm (about 0.8% of the workpiece) was obtained. The interface between the two materials was free of cavities and kissing bond. The joint fractured in thermo-mechanically affected zone on the side of AA2219-T6 alloy. The tensile strength reached 352 MPa, equal to 81.7% of base AA2219-T6 alloys.

提出了一种包含突出内肩和外肩的阶梯肩搅拌摩擦焊工具来连接 AA2195-T8 Al-Cu-Li 和 AA2219-T6 Al-Cu 合金。大切入深度的内肩增强了锻造效果，低切入深度的外肩防止了塑化材料从焊缝溢出，而带有铣削面的销促进了材料流动。获得焊缝减薄 0.05 毫米（约占工件的 0.8%）的完好接头。两种材料之间的界面没有空腔和接吻键。接头在AA2219-T6合金侧面的热机械影响区断裂。抗拉强度达到 352 MPa，相当于 AA2219-T6 基合金的 81.7%。