Deformation mechanism of Mg-Gd-Y-Zr alloy during hot ring rolling

Highlights: • The strain distribution of the ring is outer region> inner region> middle region. • Tension twinning and prismatic slip play vital roles in the middle region. • Tension twin growth and multiple slips dominate the deformation in the edge region. The strain level-dependent deformation mechanisms during hot ring rolling (HRR) were clarified by microstructural and textural heterogeneities of a large-size Mg-Gd-Y-Zr alloy in this paper. Results show that non-uniform strain distribution along the radial direction of the Mg alloy ring caused the variation in practically activated deformation mechanisms among various regions of the ring. According to the result of 3D elastic–plastic finite element model (FEM), the strain level is highest in the outer region, slightly lower in the inner region, and lowest in the middle region. We found that tension twinning and prismatic slip dominate deformation in the region with a relatively low strain level region, such as in the middle region. In the edge region with a high strain level, the main deformation behaviors include the activation and propagation of tension twins, high degree dynamic recrystallization (DRX), and multiple slip mechanisms. This work clarified the origin of the microstructural and textural heterogeneities of large-size Mg alloy ring fabricated by hot ring rolling, and revealed the deformation mechanism during the process, which sheds a light on the manufacturing of large-size Mg alloy structural components and provides a clue for improving their microstructural and mechanical homogeneity.