The evolutions of grain structure, microtexture and mechanical properties during bobbin friction stir welding of Mg-5.89 wt%Zn-0.61 wt%Zr alloy were investigated. The electron backscattered diffraction analyses revealed that the grain structure evolution was a complicated process dictated by continuous dynamic recrystallization but also involved geometrized effects of strain and {10–12} twinning. Local texture varied significantly from the parent metal to the weld nugget. With increased access to the weld nugget, the initial <0001>||ND texture gradually reoriented towards <0001>||TD and finally transformed into a near-<0001>||WD texture. Arising of the near-<0001>||WD texture was associated with the extensive continuous dynamic recrystallization and the reorientations of the recrystallized grains under the effect of shearing deformation introduced by the rotating stir probe. Microhardness distribution exhibited weak grain size dependence. Transverse tensile elongation of the joint was lower than that of the parent metal owing to strain localization in thermo-mechanically affect zone (TMAZ)/weld nugget zone (WNZ) interface region. Decomposition of β₁´ precipitates and texture evolutions in WNZ and TMAZ, as well as dislocations concentration and grain size mutation existed in the interface region corporately resulted in the inhomogeneous plastic deformation.

研究了Mg-5.89 wt％Zn-0.61 wt％Zr合金线轴摩擦搅拌焊接过程中晶粒组织，微观组织和力学性能的变化。电子背散射衍射分析表明，晶粒结构的演变是由连续动态再结晶决定的复杂过程，但也涉及应变和{10-12}孪晶的几何效应。从母材到焊核，其局部织构明显不同。随着进入焊核的增加，初始的<0001> || ND纹理逐渐重新定向为<0001> || TD，最后转变为接近<0001> || WD的纹理。<0001>附近的出现 || WD织构与广泛的连续动态再结晶以及在旋转搅拌探针引入的剪切变形的影响下，再结晶晶粒的重新取向有关。显微硬度分布表现出较弱的晶粒尺寸依赖性。由于热机械影响区（TMAZ）/熔核区（WNZ）界面区域中的应变局部化，接头的横向拉伸伸长率低于母材。β分解₁ '析出物和纹理演变在WNZ和TMAZ，以及位错浓度和粒度突变corporately导致不均匀的塑性变形的界面区域存在。