Microstructural evolution of pure copper during friction-stir welding

Abstract

The microstructural evolution of pure copper during friction-stir welding was found to be principally influenced by welding temperature. At temperatures below ~0.5 T_m (where T_m is melting point), the microstructure was shown to be essentially determined by continuous recrystallization, leading to significant grain refinement and related material strengthening in the stir zone. In contrast, grain structure development at temperatures above ~0.5 T_m was dominated by discontinuous recrystallization producing a relatively coarse grain structure in the stir zone and giving rise to material softening.

Keywords:

• copper
• friction-stir welding
• electron backscatter diffraction (EBSD)
• microstructure
• texture

Acknowledgements

The authors are grateful to Mr A. Honda for technical assistance and Dr K. Kobayashi for help with EBSD measurements. One of the authors (S. Mironov) would like to express his hearty thanks to Tohoku University for providing a scientific fellowship.

Notes

1. Here and hereafter, the reader is referred to on-line version of the paper to see the figures in colour.