Temperature and Strain Rate Dependence of Flow Stress in Severely Deformed Copper by Accumulative Roll Bonding

Abstract

Tensile tests and strain rate jump tests have been carried out at low temperatures (77 K ∼ room temperature (RT)) using pure Cu specimens that were severely deformed by accumulative roll bonding (ARB). The dependence of the flow stress on the temperature and the strain rate has been investigated and the strain rate sensitivity m and its variation caused by the change in the ARB cycle N are discussed. At RT, the strain rate sensitivity for N≤4 stays at about 0.005. However, for N≥5, m increases with increasing N to become ∼0.018 when N=8. The deformation mechanisms of the ARB processed Cu are discussed with the activation volume V^*. The temperature dependence of V^* and its variation with increasing N are also discussed.