Shear localization and recrystallization in an ultrahigh strain rate deformed copper shaped charge liner

To assess the effect of explosive loading on deformation behavior and microstructure evolution, a slug recovered from a fine-grained copper shaped charge liner after detonation deformation at an ultrahigh strain rate over 104 s−1 was investigated. In the slug, multiple shear bands appeared in a single direction spiral pattern and exhibited self-organization behavior, which constitute the main deformation characteristics. Compared with the initial fine grains, the larger grains formed in the deformed copper liner. The annealing twins and few dislocations were observed in these grains. Further, a copper texture and cube texture appeared in different parts of the slug. The results demonstrate the occurrence of recovery and recrystallization. Throughout the detonation process, a substantial amount of plastic work was transformed into heat, the copper liner underwent rapid heating. The thermal softening due to elevated temperature counteracted work hardening and induced shear localization. The existence of shear bands means that the collapsing mechanism of the liner changed from global deformation to shear localization. Although the post-deformation cooling rate of the slug was very fast, the temperature and time met the requirements of recrystallization and grain growth by grain boundary migration. Through this study, the influence of the thermal effect on ultrahigh strain rate deformation is better understood.