Comparison of annealing on microstructure and anisotropy of magnesium alloy AZ31 sheets processed by three different routes

Cold rolling and annealing treatment were applied to magnesium alloy AZ31 sheets fabricated by three processing routes: extrusion-rolling (EX), hot-rolling (HR) and twin-roll casting (TRC) in the present work to investigate the effect of annealing treatment on the microstructure evolution and mechanical anisotropy. The results showed that processing routes had a significant influence on the microstructure evolution and mechanical properties under same cold rolling and annealing conditions. The TRC sheet exhibited slight grain coarsening even when annealed up to 450 °C, while the grain growth was obviously observed in HR sheet with increasing annealing temperature. The tensile tests at room temperature indicated that the mechanical anisotropy of EX sheet was insensitive to temperature, but sharply decreased in HR sheet at elevated temperature. The fracture elongation anisotropy of all three sheets decreased with increasing annealing temperature, especially in the TRC sheet.