The effect of microstructure on the mechanical properties of friction stir welded 5A06 Al Alloy

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.