Restoration mechanisms in large-strain deformation of high purity aluminum at ambient temperature and the determination of the existence of “steady-state”

Abstract

High purity (99.999%) aluminum was deformed at ambient temperature to large strains in compression at strain rates of 10 −3 and 10 −5s −1. A saturation in the flow stress is eventually observed at both rates, but this is followed by significant softening. Analysis of the mechanical tests, optical microscopy, and transmission electron microscopy suggest that the softening is due to recrystallization during deformation. Some early investigations that report a steady-state in high purity aluminum, suggesting a balance between dynamic recovery and hardening, may have actually been a result of recrystallization. Other investigations that report a continual, Stage IV, hardening with an absence of a saturation of the flow stress or a steady-state, even at large strains, may be valid for cases where recrystallization is suppressed.