Microstructural evolution of twin-roll cast Mg–3Al–0.5Mn–0.2Mm alloys during warm rolling and subsequent annealing

Microstructure of twin-roll casted (TRC) Mg–3Al–0.5Mn–0.2Mm (or AM30 + 0.2Mm) alloy strips consisted of columnar dendrites in the surface and equiaxed dendrites in the center regions, as well as widely dispersed fine primary intermetallic compounds located in the interdendritic region. Warm rolling of the TRC strips developed both deformation or shear bands and homogeneously dispersed fine particles. No evident dynamic recrystallization (DRX) was found in the TRC sheets during warm rolling. The dispersed fine particles seemed to retard DRX. The warm-rolled TRC sheets showed equiaxed fine grains with an average size of around 8 μm after annealing at 350 °C for 60 min. The TRC sheets had superior yield and tensile strengths to ingot cast (IC) samples. Elongation was similar to both TRC and IC samples.