Hot deformation behavior and microstructural evolution of a new type of 7xxx Al alloy

Optimizing the thermal deformation parameters of Al alloys is beneficial for achieving grain refinement, avoiding microscopic defects in materials, and significantly enhancing the mechanical properties of Al alloys. In this study, the hot deformation behavior of a new type of 7xxx Al alloy was investigated through hot compression tests at strain rates of 10(-3)-1 s(-1) and temperatures of 250-420 degrees C. The constitutive equation was successfully established using the hyperbolic sine form of the Arrhenius equation, accurately describing the flow stress. The hot processing map was obtained by overlaying the power dissipation map and the instability map, determining the optimal hot working parameters to be in the range of 325-373 degrees C, 0.45-1 s(-1). In the safe region, dynamic recovery (DRV) and dynamic recrystallization (DRX) were predominant. The instability in the low-temperature region was attributed to the grain boundary pinning effect caused by grain boundary precipitation, while the instability in the high-temperature region was associated with local shear bands induced by uneven plastic strain. The hot processing map establishes a good connection with the microstructural evolution of the new type of 7xxx Al alloy under different hot deformation parameters.