Mechanism of grain structure development for pure Cu and Cu-30Zn with low stacking fault energy during FSW

Abstract

The mechanism of grain structure development for pure Cu and Cu-30Zn with a low stacking fault energy (SFE) during friction stir welding was examined by changing the peak temperatures. Increase in the peak temperature caused the inhibition of discontinuous dynamic recrystallisation (DDRX) owing to the promotion of dynamic recovery. Further, grain refinement occurred dominantly by the frequent annealing twinning. The B/ {112}⟨110⟩ simple shear texture was highly developed without the 45° rotated cube component, which originated from the DDRX. The mechanism for grain structure development, including the DDRX and the annealing twinning was determined by the ratio of peak to the recrystallisation temperature rather than the melting temperature irrespective of the pure Cu and Cu-30Zn with a low SFE.