The influence of long-term annealing at room temperature on creep behaviour of ECAP-processed copper

Present work investigates the effect of long-term annealing at low homologous temperature (~0.22 Tm) on creep behaviour of pure copper (99.99%) processed by equal-channel angular pressing (ECAP). Coarse-grained pure copper was processed by 1 and 8 ECAP passes at room temperature. The ECAP-processed specimens were annealed at room temperature for 3 years. Microstructures of ECAP-processed specimens and their room temperature-annealed states were investigated by electron back scatter diffraction (EBSD) technique. Tensile tests were performed at room temperature under constant rate and at 373 K in creep under constant load. It was found that long-term annealing at room temperature led to occurrence of large grains in microstructure which influenced the strength. The influence grew with number of ECAP passes.