Grain Size Control of Commercial Wrought Mg-Al-Zn Alloys Utilizing Dynamic Recrystallization

Abstract

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 3.3×10⁻² 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.