The kinetics of dynamic and static softening during multistage hot deformation of 7150 aluminum alloy

Isothermal continuous and interrupted hot compression tests have been carried out on Gleeble-1500 system at temperatures of 300 °C and 400 °C, strain rates of 0.01 s−1 and 0.1 s−1, respectively. The dynamic and static softening kinetics of 7150 aluminum alloy during multistage hot deformation were investigated by means of flow curves and relative softening rates. The results show that the flow curve exhibits a peak and some work softening during hot deformation of 7150 aluminum alloy. The flow stress increased with increasing strain rate and decreasing temperature while the flow softening decreased. The static softening increased with increasing strain rate, deformation temperature and delay time. The static softening curves appeared as a typical sigmoidal shape of the type at temperature of 400 °C, while plateaus were observed when temperature decreased to 300 °C. The appearance of static softening at 400 °C exceeding 100% was observed. An empirical static recrystallization model based on Johnson–Mehl–Avrami–Kolmogorov model with the recrystallization activation energy of 219.17 kJ/mol for 7150 aluminum alloy was derived.

► Isothermal continuous and interrupted hot compression tests were carried out on 7150 aluminum alloy.
► A typical sigmoidal shape appeared for the static softening curves at temperature of 400 °C.
► Plateaus were observed for the static softening curves at temperature of 300 °C.
► The appearance of static softening at 400 °C exceeding 100% was observed.
► An empirical static recrystallization model based on JMAK model was derived.