The dissimilar AM60/AZ31 Mg alloys joints were obtained via friction stir welding (FSW). Then, the upper and lower surfaces of the FSW joint were remelted by using tungsten inert gas (TIG) welding. The macrostructures, microstructure evolution and mechanical properties of the two kinds of joints were investigated. The results indicated that there was a TIG weld zone in both the upper and lower parts of the nugget zone (NZ) of the FSW joint after the arc heating. Further, the grain size in the NZ-middle grew to a certain extent, especially the area near the NZ-middle-center. Texture analysis showed that the texture in the NZ-middle was modified after the arc heating, especially in the TIG weld zones. However, there were no significant changes in texture and grain size near the NZ interface. The tensile results showed that the tensile strength and yield strength of the two joints were similar, but the joint elongation after arc heating was largely improved, by about 57%. The equivalent strength of the two kinds of joints was due to the similar texture and grain size near their NZ interfaces. The higher elongation was attributed to the increase of the Schmid factor values (basal slip and extension twinning) caused by the weakening of the texture, the growth of the grain size and the annihilation of the initial residual dislocation in the NZ-middle. As a result, the difficulty of deformation in the NZ-middle was reduced, which weakened the localized strain of the joint. This work could provide a new method for weakening the strain localization of FSW Mg joints.

通过搅拌摩擦焊（FSW）获得了不同的AM60 / AZ31 Mg合金接头。然后，使用钨极惰性气体保护（TIG）焊接对FSW接头的上下表面进行重熔。研究了两种接头的宏观结构，微观组织演变和力学性能。结果表明，电弧加热后，FSW接头的熔核区（NZ）的上部和下部均存在TIG焊接区。此外，NZ-中间部分的晶粒尺寸有一定程度的增长，特别是NZ-中间中心附近的区域。织构分析表明，电弧加热后，NZ中部的织构发生了变化，尤其是在TIG焊接区。但是，NZ界面附近的组织和晶粒尺寸没有明显变化。拉伸结果表明，两个接头的拉伸强度和屈服强度相似，但是电弧加热后的接头伸长率大大提高了约57％。两种接头的等效强度是由于其NZ界面附近的纹理和晶粒尺寸相似。较高的伸长率归因于质地弱化，晶粒尺寸的增长和NZ中部初始残余位错的an灭而导致的Schmid因子值（基部滑移和延伸孪生）的增加。结果，减少了NZ中间件的变形难度，从而削弱了接头的局部应变。这项工作可以为弱化FSW镁合金接头的应变局部化提供一种新方法。但是电弧加热后的接头伸长率得到了很大的改善，提高了约57％。两种接头的等效强度是由于其NZ界面附近的纹理和晶粒尺寸相似。较高的伸长率归因于质地弱化，晶粒尺寸的增长和NZ中部初始残余位错的an灭而导致的Schmid因子值（基部滑移和延伸孪生）的增加。结果，减少了NZ中间件的变形难度，从而削弱了接头的局部应变。这项工作可以为弱化FSW镁合金接头的应变局部化提供一种新方法。但是电弧加热后的接头伸长率得到了很大的改善，提高了约57％。两种接头的等效强度是由于其NZ界面附近的纹理和晶粒尺寸相似。较高的伸长率归因于质地弱化，晶粒尺寸的增长和NZ中部初始残余位错的an灭而导致的Schmid因子值（基部滑移和延伸孪生）的增加。结果，降低了NZ中间件的变形难度，从而削弱了接头的局部应变。这项工作可以为弱化FSW镁合金接头的应变局部化提供一种新方法。较高的伸长率归因于质地弱化，晶粒尺寸的增长和NZ中部初始残余位错的an灭而导致的Schmid因子值（基部滑移和延伸孪生）的增加。结果，降低了NZ中间件的变形难度，从而削弱了接头的局部应变。这项工作可以为弱化FSW镁合金接头的应变局部化提供一种新方法。较高的伸长率归因于质地弱化，晶粒尺寸的增长和NZ中部初始残余位错的an灭而导致的Schmid因子值（基部滑移和延伸孪生）的增加。结果，减少了NZ中间件的变形难度，从而削弱了接头的局部应变。这项工作可以为弱化FSW镁合金接头的应变局部化提供一种新方法。