Effect of Initial Microstructure States on Flow Behavior of Al-Zn-Mg-Cu Alloy During Hot Tensile Deformation

Abstract:

To investigate the influence of Al-Zn-Mg-Cu alloy with as-homogenized and as-rolled initial microstructures on the tensile flow behavior, isothermal tensile tests were conducted on a GLEEBLE-3500 isothermal simulator at temperatures of 380–440 °C and strain rates of 0.05–1 s^-1. The Johnson-Cook model, Hensel-Spittel model, strain-compensated Arrhenius model, and critical fracture strain model were established. Results show that through the evaluation of the models using the correlation coefficient (R) and the average absolute relative error, the strain-compensated Arrhenius model can represent the flow behavior of the alloy more accurately. Shear bands are more pronounced in the as-homogenized specimens, whereas dynamic recrystallization is predominantly observed in as-rolled specimens. Fracture morphology analysis reveals that a mixed fracture mechanism is prevalent in the as-homogenized specimen, whereas a ductile fracture mechanism is predominant in the as-rolled specimen. The processing maps indicate that the unstable region is reduced in the as-rolled specimens compared with that in the as-homogenized specimens. The optimal hot working windows for the as-homogenized and as-rolled specimens are determined as 410–440 °C/0.14–1 s^-1 and 380–400 °C/0.05–0.29 s^-1, respectively.