Partial recrystallization in the nugget zone of friction stir welded dual-phase Cu–Zn alloy

Abstract

For single and quasi-single phase metallic materials, complete dynamic recrystallization has been observed in the nugget zones (NZs) of friction stir welds (FSWs), producing fine and uniform equiaxed grains. In this study, partial dynamic recrystallization was observed in the NZ of 5 mm thick friction stir welded brass plates. Whereas the top and the advancing side of the NZ were characterized by fine completely-recrystallized grains, the remaining region consisted of coarse non-recrystallized deformed grains, annealed recrystallized grains and deformed recrystallized grains. The occurrence of partial recrystallization was attributed to the inhibiting effect of a high volume fraction of fine β′-phase particles. Increasing the FSW passes reduced the fraction and size of non-recrystallized deformed grains, but could not eliminate the partially recrystallized zone completely.

Keywords:

• friction stir welding
• copper alloy
• recrystallization
• electron backscatter diffraction

Acknowledgements

This work was supported by the National Outstanding Young Scientist Foundation under Grant No. 50525103, the National Basic Research Program of China under Grant No. 2006CB605205, and the Hundred Talents Program of Chinese Academy of Sciences.