Mechanical Responses and Dynamic Recrystallization Mechanism of A356 Alloy during Single and Double Isothermal Compression Processes

The impacts of loading conditions on the mechanical response and DRX of A356 during single and double thermal compression were investigated. The results indicate that the strain hardening rate obtained during the second isothermal compression is far larger than that obtained during the initial isothermal compression. The microstructure after both single and double compression is dominated by deformed columnar grains and equiaxed recrystallized grains. The recrystallization fraction of the samples after double compression is greatly affected by its initial dislocation density and microstructure state. The microstructure examination shows that the evolution of the subgrain boundaries around the original grain boundaries and within the deformed columnar grains is the main mechanism for recrystallized grain formation in the A356 alloy.