The High-Temperature Deformation Mechanism in Pure Metals

In order to examine the idea that the high-temperature deformation of pure metals is recovery-controlled, strain rate change tests and stress relaxation tests have been performed using vanadium, aluminium, copper and α-iron.The work hardening rate without the recovery effect, h, and the recovery rate, r, are determined at a given deformation state by a stress relaxation test. Slopes of the stress-strain curve immediately after the strain rate change can be calculated from the values of h and r. The calculated slopes agree well with the experimentally determined slopes. The activation energy for recovery determined from stress relaxation tests agrees approximately with the activation energy for self-diffusion. Transmission electron microscopic observations on vanadium suggest that the stress change Δσ accompanying a rapid strain rate change is related to the local variation of the dislocation density.From these results, it is discussed that the high-temperature deformation of these pure metals can be understood by the recovery-controlled mechanism.