Hot Deformation Behavior of Aluminum Alloys AA7010 and AA7075

The hot deformation behavior of high-strength aluminum alloys AA7010 and AA 7075 was studied through hot isothermal compression testing in the temperature regime of 623-723 K (at an interval of 25 K) and at varying strain rates (0.001 to 10 s(-1)). The safe zone of hot workability of both the alloys was determined using the instability criteria and correlating with the microstructure evolution. Zener-Hollomon parameters were calculated, and constitutive equations were also derived. Common characteristics observed in both the alloys were adiabatic shear band formation at a temperature of 623 K and strain rate of 10 s(-1) and flow localization at combination of all temperatures and high strain rate of 10 s(-1) with evolution of very fine recrystallized (DRX) grains. High-temperature resistance to deformation, large extent of recrystallization and relatively larger zone of stable deformation and higher activation energy in Al alloy AA7010 were observed as compared to AA7075. Considering the role of precipitates, dynamic recrystallization was found to have significant role in governing the hot deformation behavior of the alloys. Prediction of constitutive equations was found to be more accurate at higher temperatures and at moderate-to-high strain rates with relatively less error in AA7075 alloy as compared to AA7010 alloy.