Effect of initial microstructure on hot workability of 7085 aluminum alloy

The hot workability of 7085 aluminum alloys with different initial microstructures (as-homogenized and as-solution treated) was studied by isothermal compression tests at the deformation temperature ranging from 300 to 450 °C and the strain rate ranging from 0.0001 to 1 s−1. The strain rate sensitivity of the alloy was evaluated and used for establishing the power dissipation maps and instability maps on the basis of the flow stress data. The results show that the efficiency of power dissipation for the as-homogenized alloy is lower than that of the as-solution treated alloy. The deformation parameters of the dynamic recrystallization for the as-homogenized and as-solution treated alloy occur at 400 °C, 0.01 s−1 and 450 °C, 0.001 s−1, respectively. The flow instability region of the as-homogenized alloy is narrower than that of the as-solution treated alloy. These differences of the alloys with two different initial microstructures on the processing maps are mainly related to the dynamic precipitation characteristics.