Macroscopic non-uniform deformation is usually found in deformed joints of friction sir welded (FSW) wrought Mg alloys, detrimental to the joint performance. In the present work, two kinds of FSW joints with different stirred zone (SZ) structures were generated for extruded AZ31 plates. Comparative studies were conducted aiming to unravel the underline mechanism of the non-uniform deformation and their effect on tensile properties. It was found that the occurrence of non-uniform deformation was associated with the special texture distribution and twinning behavior in the SZ. The shape of concave sub-regions in the SZ coincided with the distribution area of extension twins. Texture evolution showed that consistent lattice rotation occurred across the SZ during tensile process. Schmid factor analysis revealed the role acted by basal slip and extension twinning in sub-regions at various deformation stages. In addition, the non-uniform deformation behavior could be suppressed by modifying the texture distribution through increasing the tool rotation rate, which meanwhile could improve both the tensile strength and ductility of the joints. Digital image correlation measurements provided detailed examination of the actual strain distribution evolved in the joints and demonstrated the dominant contribution of strain localization to the tensile properties.

通常在变形的Sir焊接（FSW）变形Mg合金变形接头中发现宏观不均匀变形，这对接头性能是有害的。在本工作中，为挤压的AZ31板生成了两种具有不同搅拌区（SZ）结构的FSW接头。进行了比较研究，旨在揭示非均匀变形的底线机理及其对拉伸性能的影响。发现在深圳，不均匀变形的发生与特殊的纹理分布和孪生行为有关。SZ中凹形子区域的形状与延伸双胞胎的分布区域一致。纹理演变表明，在拉伸过程中，整个SZ发生了一致的晶格旋转。施密特因子分析揭示了基底滑移和伸展孪生在各个变形阶段的子区域中的作用。此外，通过提高工具旋转速率来改变纹理分布，可以抑制不均匀的变形行为，同时可以提高接头的抗拉强度和延展性。数字图像相关测量提供了对接头中实际应变分布的详细检查，并证明了应变局部化对拉伸性能的主要贡献。同时可以提高接头的抗拉强度和延展性。数字图像相关测量提供了对接头中实际应变分布的详细检查，并证明了应变局部化对拉伸性能的主要贡献。同时可以提高接头的抗拉强度和延展性。数字图像相关测量提供了对接头中实际应变分布的详细检查，并证明了应变局部化对拉伸性能的主要贡献。