Regulation of high-temperature microstructure evolution and recrystallization by pre-strain accumulation in Al–Zn–Mg–Cu alloys

Abstract

This study systematically investigates the hot deformation behavior of Al–Zn–Mg–Cu alloy through pre-deformation compression tests at different temperatures (room temperature, RT, and cryogenic temperature, CT) with varying pre-strain levels, combined with isothermal hot compression experiments. The deformation characteristics were examined under specific conditions: deformation temperature of 440 °C, strain rates of 0.001 s −1 and 0.1 s −1 , and a deformation degree of 60 %. Electron backscatter diffraction (EBSD) characterization was employed to examine the microstructure of both pre-deformed and isothermally compressed specimens. This study provided a detailed investigation into the deformation characteristics of the materials after different pre-deformation treatments and their influence on the dynamic recrystallization (DRX) behavior and substructural evolution during subsequent high-temperature deformation. The results demonstrate that pre-deformation process parameters exert significant influence on strain accumulation/stored energy behavior and recrystallization characteristics in Al–Zn–Mg–Cu alloy. Both room-temperature and cryogenic pre-deformation treatments induce the formation of high-density micro-shear bands within deformed grains, whose density exhibits positive correlation with increasing pre-strain levels. Under the same pre-strain level, cryogenic pre-deformation induces more strain energy accumulation and leads to more uniform plastic deformation. The strain energy accumulated through pre-deformation effectively facilitates the occurrence of DRX during subsequent hot deformation, and it enables effective control of the high-temperature deformation microstructure by influencing DRX behavior. This study systematically clarifies the intrinsic correlation between pre-deformation-induced strain accumulation characteristics and high-temperature deformation-recrystallization behavior in Al–Zn–Mg–Cu alloys. Furthermore, it reveals the microstructural evolution patterns and recrystallization regulation mechanisms during high-temperature deformation of pre-deformed Al–Zn–Mg–Cu alloys. These findings provide theoretical guidance for optimizing thermo-mechanical processing parameters in advanced aluminum alloy manufacturing technologies.

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