The effect of grain size, grain orientation and precipitates on mechanical properties of friction stir welded 5A06 aluminum alloy was investigated with varying rotation speeds. The precipitation behavior and grain coarsening were discussed. Recrystallization occurred in the weld zones and recrystallization texture components were replaced by the shear texture components with increased rotation speeds. The development of shear texture, precipitates dissolution, and dislocations pinned by precipitates may result in the coarsening of the grains in the weld zones at higher rotation speeds. The effect of grain size on hardness is consistent with Hall-Petch relationship. All the welds fractured in the boundary between TMAZ and the HAZ at the AS due to the dislocations pinned by the precipitates and the sharp change of microstructure at the AS.

研究了不同转速下搅拌摩擦焊接5A06铝合金的晶粒尺寸，晶粒取向和析出物对力学性能的影响。讨论了沉淀行为和晶粒粗化。在焊接区域中发生再结晶，并且随着旋转速度的增加，再结晶织构成分被剪切织构成分所取代。剪切织构的发展，析出物的溶解以及由析出物引起的位错可能会导致在较高转速下焊缝区域晶粒的粗化。晶粒尺寸对硬度的影响与霍尔-帕奇关系一致。由于析出物引起的位错和AS的显微组织的急剧变化，在AS的TMAZ和HAZ之间的边界处的所有焊缝均断裂。