Characterization of hot deformation behaviors of wrought and P/M oxygen free coppers (OFCs) using processing maps

摘要

Wrought and powder sintered (P/M) oxygen free coppers (OFC) were subjected to hot deformation testing over the range of strain rates (0.01-10.0 s~(-1)) and temperatures (200-800℃). Processing maps of both materials have exhibited different deterministic domains representing dynamic recrystallization (DRX), which occurs in the following temperature and strain rate ranges: for wrought copper, 400-600 ℃ and 0.01-0.1 S~(-1), 600-800℃ and 0.01-10.0 s~(-1); for P/M one, 600-800℃ and 0.01-1.0 ~(-1). The domain for wrought copper has higher efficiency of power dissipation with increasing temperature and decreasing strain rate. For P/M OFC, the region at temperature of 600℃ and strain rate of 10~(-2) s'showed peak efficiency. The results on processing maps have well correlated with those obtained from kinetic analysis. The apparent activation energies estimated in the DRX domains are 146.04 and 190.67 kJ/mol for wrought and P/M OFCs, respectively, which suggest that dislocation core diffusion and lattice self-diffusion are the rate controlling mechanism each. In all domains, the average grain diameter varies linearly with Zener-Holloman parameter.