Microstructure and deformation behavior of extruded 7A43 alloy in solid solution state under room temperature compression

The compression deformation test on extruded-solid solution 7A43 alloy (Al-6.0Zn-2.1Mg-0.15Cu-0.15Zr, mass fraction/%) was conducted by Gleeble-3500 machine with strain rate of 0.001 s-1 to 1 s-1 at room temperature, and the microstructural features were characterized by scanning electron microscopy (SEM), backscattered electron microscopy (EBSD) and X-ray differaction analysis (XRD). It is revealed that with the increase of strain rate, the average grain size decreases due to severe microstructural distortion, whilst the lattice strain and dislocation density in the alloy gradually increase. Dynamic recovery substructure components in the microstructure are enhanced, and the coarse deformed grains are replaced by fine equiaxed grains under high deformation rate conditions. A Fields-Backofen (F-B) constitutive model was constructed based on the experimental stress-strain data, the correlation coefficient (R) and average absolute relative error (AARE) between the experimental and predicted values are 0.991069 and 3.667%, respectively, which provide a good description of the model for deformation rheological behavior of 7A43 aluminum alloy at room temperature.