Kinetics and dynamics of hot deformation of OFHC copper in extended temperature and strain rate ranges

The hot-deformation behavior of oxygen-free high-conductivity (OFHC) copper has been studied in the temperature range 300-950°C and strain rate range 0.001-100 s^-1 using hot-compression tests. The dynamics of the behavior is studied with the help of processing maps, and the-rate controlling processes are evaluated using the standard kinetic rate equation. The processing maps exhibited two domains: (1) in the temperature range 600-900°C and strain rate range 0.01-10 s^-1, (2) in the range 750-950°C and 30-100 s^-1. From kinetic analysis of the flow stress data, apparent activation energy values of 159 kJ/mole and 75 kJ/mole have been estimated in the above two domains, respectively. These values suggest that dislocation core self-diffusion and grain boundary self-diffusion are the rate-controlling mechanisms. In both these domains, the average grain diameter varies linearly with the Zener-Hollomon parameter.