A New Analytical Model for the Flow Stress of Twin-roll Casting Magnesium Sheet at Elevated Temperatures

To evaluate the flow stress of the twin-roll casting magnesium sheet in high temperature forming processes, a new analytical model was proposed by analyzing stress-strain curves measured under various temperatures and strain rates. The model can be parameterized to reflect the volume fraction of semi-sold grain and sold grains undergoing twinning. By applying the new model, the result showed that the simulated stress-strain curves fit the experiment data very well. Such curve fitting can be employed for any magnesium sheet when the deformation conditions are known. Microstructure evolution indicated that it affected the stress-strain curves directly. The mechanisms of dynamic recrystallization (DRX) depended on the operating deformation mechanisms, which changed with temperatures. And the volume fraction and grain size of DRX changed with the Zener-Hollomon parameter and temperatures.