Grain size control of commercial wrought Mg-Al-Zn alloys utilizing dynamic recrystallization

Dynamic recrystallization (DRX) behavior was systematically examined in two commercial Mg-Al-Zn alloys in order to clarify the relationship between deformation conditions and the resulting microstructure. The materials were deformed by upset forging at temperatures ranging from 473 to 673 K at an initial strain rate of 3.3 x 10(-2) s(-1). Grain refinement was observed during deformation. It was found that the dynamically recrystallized grain size decreases with an increasing Zener-Hollomon parameter and/or a decreasing initial grain size. A phenomenological constitutive equation was developed in order to provide a guideline for the control of the grain size of hot deformed AZ61 alloy.