Self-Annealing Phenomena in the Cold-Rolled and Cryo-Rolled Copper Alloys: A Review

Abstract

Severely deformed copper (Cu) alloys showed the self-annealing behaviour when exposed at room temperature (RT) for a prolonged time. This phenomenon results in the evolution of self-annealed grains, dislocations annihilations, and a decrease in the strength. The present review work addresses the evolution of self-annealed microstructures in room-temperature-rolled (RTR) and cryogenic-rolled (CR) Cu alloys, including various grades of Cu alloys such as ETP Cu, Cu-Fe-P, Cu-Sn-Mg alloys that were studied in terms of RT softening. Static recrystallization (SRX) at room temperature (RT) was observed in the highly deformed RTR and CR Cu alloy samples. Both discontinuous SRX (DSRX) and continuous SRX (CSRX) were responsible for the nucleation of small grains at RT. Particle-stimulated nucleation (PSN) also contributed to small-grain formations around Cu2O particles in ETP Cu. However, no PSN was reported for the Cu-Fe-P and Cu-Sn-Mg alloys. The formation of strain localizations (SLs) and shear bands (SBs) was observed in the deformed Cu alloys; these sites were preferred for grain nucleation during RT recrystallization.