EBSD characterization of repetitive grain refinement in AZ31 magnesium alloy

• Boundaries and sub-boundaries evolutions were characterized.
• Discontinuous recrystallization was operative at initial stages of deformation.
• A novel repetitive grain refinement trend was realized.

A polycrystalline Mg–3Al–1Zn was subjected to high plastic strains by applying accumulative back extrusion (ABE) process. Electron back scatter diffraction analyses were used to explore the grain refinement mechanisms. A novel grain refinement trend was found at large strains, where new recrystallized grains were repetitively refined through dynamic recrystallization. The grain size was diminishing continuously up to the fourth ABE pass, after which no further grain refinement was noticed upon successive passes.