Processing maps for hot working of ZK60 magnesium alloy

The hot working behavior of ZK60 magnesium alloy by squeeze casting has been studied in the temperature range of 523-723 K and strain rate range of 0.001-10 s^-1 by establishing processing maps. The strain rate sensitivity (m), power dissipation efficiency (η) and instability parameter (ξ (over(ε{lunate}, ̇))) were computed based on the experimental compression data and are plotted in the temperature-strain rate plane to obtain power dissipation and instability maps. The power dissipation map reveals that a domain of dynamic recrystallization (DRX) occurred in the temperature range of 573-648 K and strain rate range of 0.001-0.01 s^-1, with its peak efficiency of 36% at 648 K and 0.001 s^-1, which are the optimum hot working parameters. Analysis of the flow behavior and microstructure observations indicated that dynamic recrystallization occurred at higher temperatures and lower strain rates. Instability map showed flow localization at lower temperatures and higher strain rates.