Hot deformation behavior and its effect on microstructure evolution of aluminum cladded 7B04 composite sheet

Hot compression properties of aluminium cladded 7B04 composite sheets were investigated by thermal simulation testing at the deformation temperatures of 380-450 ℃ and strain rates of 0.1-30 s-1. The results show that the instability zone of hot processing map gradually expands to the region of high strain rates with the increase of true strains. The most suitable hot working zone is at the temperature range of 380-410 ℃ and strain rate of 5-30 s-1. Electron backscattered diffraction (EBSD) technique was employed to study the deformed microstructure. The results show that the recrystallized grains tend to have flat boundaries and the orientation difference between grain boundaries increases gradually with the increase of temperature and the decrease of strain rate. During deformation, the Al-clad layer shows mainly continuous dynamic recrystallization, while discontinuous dynamic recrystallization and continuous dynamic recrystallization (including geometric dynamic recrystallization) co-exist in the 7B04 matrix. The optimal hot deformation temperature of materials are 410 ℃ at the strain rate of 10 s-1, at this moment, the grain size of both 7B04 matrix and Al cladding is close and small