Mathematical modelling of billet casting with secondary cooling zone electromagnetic stirrer

Abstract

A three-dimensional unsteady coupled mathematical model has been applied to analyse the turbulent flow, temperature fields and macroscopic solidification of molten steel in billet continuous casting with electromagnetic stirring (EMS). Induction currents caused by fluid flow and the stirrer end effect have been investigated. The Lorentz force and Joule heat caused by induction currents have also been taken into account. The application of EMS in the secondary cooling zone results in significant changes in molten steel flow and temperature distribution, and the flow patterns on the horizontal cross-section agree well with the results in other references. Joule heat and Lorentz force are mainly located at the surface layer of the billet and decrease rapidly with penetration depth. The degree of superheat is reduced or eliminated rapidly when molten steel is stirred by EMS, hence is beneficial to generate more equiaxed grains. Stirring intensity is highest in the regions near the two ends of the stirrer. The Joule heat produced by induction has limited influence and can be ignored. The industrial trials showed that the EMS can effectively suppress the central shrinkage cavity and the centre C segregation to improve product quality.