Effect of Mold Electromagnetic Stirring on Metallurgical Behavior in Ultrahigh Speed Continuous Casting Billet Mold

A three-dimensional model of fluid flow, heat transfer, solidification, and inclusion motion in billet mold at ultrahigh casting speed under electromagnetic field is developed. The low Reynolds number k–ε model coupled with electromagnetic model and Lagrangian discrete phase model is used to investigate the flow field, temperature field, solidification, and inclusions transport under different current intensities. The results show that mold electromagnetic stirring (M-EMS) significantly alters the flow pattern of molten steel. The impact depth of the molten steel decreases as the stirring current intensity increases, and the horizontal swirl intensities of the molten steel increase with the stirring current intensity. As the current intensity increases from 500 to 700 A, the impact depth decreases from 0.637 to 0.575 m and the maximum tangential velocity increases from 0.477 to 0.898 m s⁻¹. When the stirring current is intense, the flow of molten steel near the mold exit is reversed, and the molten steel flows asymmetrically and unsteadily. The M-EMS effectively improves the transverse heat transfer of the molten steel in the mold, contributing to the dissipation of the molten steel superheat and the growth of the solidified shell. In addition, the removal ratio of the inclusions is improved significantly.