Hot deformation behavior and microstructure evolution model of 7055 aluminum alloy

Hot compression tests were conducted on 7055 aluminum alloy under different strain rates, temperatures, and reduction ratios. The influence of deformation parameters on microstructure evolution and hot deformation behavior was studied through EBSD and TEM characterization. An Arrhenius constitutive model was established and the recovery and recrystallization characteristics of the alloy under different conditions were analyzed. Results showed that the softening mechanism during the hot compression process of 7055 aluminum alloy was mainly attributed to recovery and partial recrystallization. The Zener-Holloman (Z) parameter was utilized to reveal the combined effects of strain rate and temperature on recrystallization behavior. Under conditions of high LnZ values (20 < LnZ), the alloy exhibited predominantly discontinuous dynamic recrystallization (DDRX) characteristics, while at low LnZ values (14 < LnZ < 17), it displayed significant continuous dynamic recrystallization (CDRX) characteristics. The alloy showed a coexistence of CDRX and DDRX phenomena under conditions of moderate LnZ values (17<LnZ <20). In addition, based on the characterization, statistical analysis, and examination of the hot-compressed microstructure of the 7055 aluminum alloy, models for recrystallization fraction, grain size evolution, and deformed grain size were established, and an average grain size model was further developed. Comparison between the finite element simulation results based on the models and experimental results demonstrated good agreement in predicting the average grain size.