2-D MATHEMATICAL ANALYSIS OF VERTICAL TWIN-ROLL CASTING FOR MAGNESIUM ALLOYS

Recently, vertical twin-roll casting that combines solidification and rolling has been used to produce magnesium alloy sheets. However, careful control is required due to the simultaneous occurrence of heat transfer, solidification, fluid flow, and solid deformation in the process. The present study applied the rigid-thermoviscoplastic finite-element method to analyze this process for magnesium alloy AZ31. Assumptions included no variations along the width direction of the melt. The study modeled the melt flow between two rolls, emphasizing the importance of solidification timing; premature solidification leads to increased hardness, while delayed solidification hampers the ability to achieve the desired thickness. A schematic of the process is provided, detailing the critical parameters such as gap thickness, nozzle thickness, melt height, and roll gap height. The analysis incorporated relationships between shear stress, shear strain-rate, and the material properties of magnesium alloy AZ31 based on existing literature. This work aims to enhance the understanding of the twin-roll casting process, ultimately contributing to improved manufacturing techniques for magnesium alloys.