Rate controlling mechanisms in hot deformation of 7A55 aluminum alloy

The hot deformation behavior of 7A55 aluminum alloy was investigated at the temperature ranging from 300 °C to 450 °C and strain rate ranging from 0.01 s−1 to 1 s−1 on a Gleeble–3500 simulator. Processing maps were established in order to apprehend the kinetics of hot deformation and the rate controlling mechanism was interpreted by the kinetic rate analysis obeying power-law relation. The results indicated that one significant domain representing dynamic recrystallization (DRX) existed on the processing maps and lying in 410–450 °C and 0.05–1 s−1. The conclusions of kinetic analysis correlated well with those obtained from processing maps. The apparent activation energy values calculated in the dynamic recrystallization (DRX) domain and the stability regions except dynamic recrystallization (DRX) domain were 91.2 kJ/mol and 128.8 kJ/mol, respectively, which suggested that grain boundary self-diffusion and cross-slip were the rate controlling mechanisms.