Mechanisms of grain refinement in Mg–6Al–1Zn alloy during hot deformation

Mechanisms of grain refinement were investigated in an extruded Mg–6Al–1Zn alloy during hot compression at 623 K and a true strain rate of 3 × 10−3 s−1. With increasing strain, grain fragmentation gradually took place; the dominant grain refinement mechanism, however, depended on the strain. At strains up to ɛ = 0.1, mechanical twinning contributed notably to grain refinement and to the formation of high angle boundaries. At medium to high strains, continuous dynamic recrystallization took place. Kinking contributed to grain fragmentation at all strains. The latter two mechanisms also increased the fraction of low to medium angle boundaries.

► High temperature deformation behavior of Mg alloy.
► Complicated grain refinement mechanisms in AZ61Mg alloy.
► Grain refinement by twinning, kinking and continuous dynamic recrystallization.
► Strain dependence of the dominant grain refinement mechanisms.