Recrystallization mechanism and anisotropy regulation of AZ31 magnesium alloy curved components by staggered extrusion

Abstract

To clarify the mechanical anisotropy of magnesium alloy curved components under complex stress states, as well as the issues that limit their service stability and reliability in lightweight equipment. The present study investigates the evolution of anisotropy through staggered extrusion (SE). By implementing coordinated control over grain morphology, texture dispersion, and slip behavior, the SE process facilitates recrystallization, resulting in the transformation of plate-like grains into fine, equiaxed structures, while simultaneously diminishing the basal texture. At an extrusion ratio (λ) of 22.4, grain orientation becomes highly dispersed, thereby promoting the activation of non-basal slip systems and enhancing mechanical consistency across various directions. The anisotropy index (Δr) is observed to decrease to 0.11, signifying an improvement in isotropy. However, excessively high extrusion ratio (λ = 44.8) leads to thermal accumulation, which can cause grain coarsening and partial texture recovery, resulting in a slight increase in anisotropy. This study elucidates the relationship between microstructural evolution and slip behavior induced by SE processing, which governs mechanical anisotropy. The findings provide a theoretical foundation for the design of curved magnesium alloy components that exhibit enhanced isotropy and service reliability.