Effects of precipitates on recrystallization of Al–Mg–Si alloy during hot deformation and sub-grain rotation behavior in dynamic recrystallization

Dynamic recrystallization (DRX) is one of the most significant microstructural features during thermal deformation. However, systematic studies on the microstructural evolution during its nucleation remain insufficient. In this work, the influence of Mg₂Si precipitates on recrystallization in Al–Mg–Si alloy during hot deformation was investigated, and the sub-grain rotation behaviors associated with different DRX nucleation mechanisms were further characterized. Results show that Mg₂Si formed under deformation conditions of 450 °C/0.001 s⁻¹ promotes recrystallization. Continuous DRX (CDRX) grains originating within grain interiors and at grain boundaries exhibit opposite lattice rotation directions, whereas geometric DRX (GDRX) grains display random rotation orientations. Discontinuous DRX (DDRX) occurs without lattice rotation, being governed primarily by grain boundary migration. Notably, CDRX nucleation requires a greater sub-grain rotation angle than GDRX. This work presents the first detailed examination of the effects of cubic Mg₂Si precipitates on recrystallization and provides a systematic characterization of sub-grain rotation behaviors in CDRX and GDRX, offering new insights into the thermal deformation mechanisms of Al–Mg–Si alloys.