Constitutive characteristics and microstructure evolution of 7150 aluminum alloy during isothermal and non-isothermal multistage hot compression

Isothermal and non-isothermal multistage hot compression tests were carried out on 7150 aluminum alloy at temperature range of 325–425 °C and strain rate range of 0.01−1 s−1. During isothermal multistage hot compression, the flow stress decreased with increasing temperature, accumulative strain as well as decreasing strain rate and pass strain. However, the interval time had a complex influence on flow stress, which ascended flow stress values with increasing interval time at 425 °C. The isothermal and non-isothermal constitutive characteristics were studied based on hyperbolic-sine law, indicating complex influences of various processing parameters on material constants. Non-isothermal multistage flow stresses were found to be easier than normal continuous single pass method to manipulate for constitutive equations calculation with better linear fitting reference and comparable activation energy. Precipitation at low temperature and its dissolution at high temperature were found to affect flow behavior and constitutive characteristics remarkably based on microstructural observation of deformed sample.