Dynamic precipitation and recrystallization behavior during hot deformation of Al-Zn-Mg-Cu alloy: Experiment and modeling

Featured with various excellent mechanical properties, the high strength Al-Zn-Mg-Cu alloys (7xxx series) have become one of the most widely-used metal materials. During the hot processing of 7xxx alloys, the high stacking fault energy and alloying element concentration can lead to the simultaneous occurrence of several physical mechanisms including the dynamic recovery (DRV), dynamic recrystallization (DRX), dynamic precipitation (DPN), and their interactions. Such complex microstructural mechanisms are difficult to be characterized and modeled in both of the experimental and theoretical aspects. In present work, aiming at 7055 alloy subjected to uniaxial hot compression, the systematic experiment investigation is first conducted to reveal hot deformation behaviors. Based on experimental analysis, a unified crystal plastic (CP) model, incorporating the DRX and DPN, is proposed by combining the viscoplastic self-consistent (VPSC) framework. In the unified model, the DRX and DPN behaviors are described by a physical based continuous dynamic recrystallization (CDRX) model and the classical Kampmann-Wagner numerical (KWN) model, respectively, and the effect of DPN on CDRX is specially modeled. After identifying the model parameters, the unified model can reasonably capture the essential features of DPN, DRX, and mechanical response under different deformation temperatures. Therefore, this study offers an innovative modeling approach for the dynamic evolution of several physical processes, facilitating the further understanding for the hot deformation behaviors of aluminum alloys.