Hot deformation characterization of a novel Al-Zn-Mg-Cu aluminum alloy through processing map and microstructure evolution

The isothermal compression experiments of a novel 7A36 aluminum alloy were performed on Gleeble3500 thermal simulation equipment at temperature range of 350 degrees C similar to 450 degrees C with an interval of 25 degrees C and strain rates of 0.01 s(-1) similar to 10 s(-1). The influence of deformation conditions on flow stress, microstructure and thermal process performance were investigated. The constitutive equation and processing map were established. The optical microscopy (OM), field emission scanning electronmicroscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the microstructure evolution. The results indicate that 7A36 aluminum alloy has steady rheological characteristics and a trend to dynamic softening. The alloy has positive strain sensitivity, the flow stress decreases with increasing of deformation temperature and decreasing of strain rate. The estimated activation energy in constitutive model is 153.703 kJ mol(-1) which is close to that self diffusion in pure aluminum. The constitutive equation and microstructure evolution during isothermal compression process confirmed that dynamic recrystallization (DRX) should be the soften mechanism. The processing map exists two safe regions of domain 1 (380 similar to 450 degrees C, 1 similar to 10 s(-1)) and domain 2 (350 similar to 450 degrees C, 0.01 similar to 1 s(-1)). The specimens deformed at 450 degrees C/0.01 s(-1) in domain 2 is proposed to be the optimum hot-working condition.