Simulation study on the influence of the combined application of melt shearing and electromagnetic field on the flow and temperature fields during Direct-Chill casting of 2024 aluminum alloy

Abstract

In the direct-chill casting, the combined application of intensive melt shearing and magnetic field can significantly enhance the grain refinement of the ingot. Understanding the changes in the melt flow and temperature distribution under the influence of the combined fields is crucial for studying the mechanisms of grain refinement. COMSOL was employed to perform numerical simulations of the flow and temperature fields in the DC casting of φ300 mm 2024 aluminum alloy ingots under different intensities of melt shearing, intensities of the magnetic field, and casting speeds. The results indicate that under the combined influence of intensive melt shearing and the magnetic field, at a constant rotor rotation speed, as the current intensity of the magnetic field coil increases, the flow direction of the melt ejected from the stator gradually deflects upward, the melt flow velocity in the center of the sump slightly decreases, and the flow velocity near the edge significantly increases, leading to the reduction of the sump depth. At a constant current intensity of the magnetic field coil, the increase of the rotor rotation speed enhances the flow velocity of most of the melt within the sump and also reduces the sump depth. Furthermore, the application of the combined fields significantly enhances heat transfer at the edge of the ingot and the solidification front, which directly contributes to the reduction of the sump depth. Under the influence of the combined fields, with the casting speed increases from 65 mm/min to 75 mm/min, 85 mm/min, and 95 mm/min, the overall flow velocity distribution in the sump becomes more uniform, the overall temperature of the melt increases, the liquid sump increases from 101 mm to 122 mm, 139 mm, and 165 mm.