Influence of strain rate on dynamic recrystallization behavior and hot formability of basal-textured AZ80 magnesium alloy

This work investigates the strain rate dependence of deformation and dynamic recrystallization (DRX) behaviors of basal-textured AZ80 magnesium alloy, in the hot compressions at 350 °C with varying strain rates of 10⁻³ s⁻¹ and 10 s⁻¹. Hot compressed microstructure was characterized using electron backscatter diffraction (EBSD) with grain-based analytical approaches, providing insights into the operative dynamic recrystallization mechanisms and correlated texture evolution. At small strain levels, discontinuous DRX mechanism was dominant at 10⁻³ s⁻¹ and stress concentrations between the neighboring grains were effectively relieved by grain boundary bulge and growth of DRXed nucleus. In contrast, at 10 s⁻¹, twin-induced DRX and continuous DRX mechanisms were activated. Off-basal-oriented grains (soft) were consumed rapidly by the operative DRX processes, while basal-oriented grains (hard) show less tendency to recrystallize. At the interphase between the residual basal-oriented grain and the neighboring DRXed grains, intergranular micro-cracks initiated in the incipient stage of the hot compression at 10 s⁻¹, due to the absence of effective strain releasing mechanism. The results have implications for hot workability improvement for AZ80 magnesium alloy under high-strain-rate conditions.