A novel approach to predict the inclusion removal in a billet caster mold with the use of electromagnetic stirrer

Abstract

Use of in-mold electromagnetic stirrer (M-EMS) in continuous casting (CC) mold has been an effective means to get clean steel. However, at times their application results in slag entrainment and inclusion particles from the meniscus due to improper positioning of the stirrer along the length of the mold. More importantly, the inclusion particles coming through the tundish outlet pose a great challenge as they are likely to get trapped in the swirl flow developed due to the stirrer and finally move towards the mold outlet. In this study, a multiphase model involving solidification, slag-metal interface and inclusion transport is developed in the billet continuous casting process. The multiphase study involves the study of slag metal interface as well as the inclusion transport in the billet caster mold. For inclusion removal at the interface, a new realistic approach based on volume fraction criterion is adopted and incorporated using user defined function. The numerical results reveal that both intensity and size of the recirculation loop decrease on shifting the EMS away from meniscus. Tangential velocity increases significantly in the presence of EMS. Stirring generated due to EMS decreases the temperature and increases the uniformity in liquid fraction in the region above the stir. This region becomes wider as EMS moves downwards. Stirring pulls down most of the interface originated 2 μm and a few 100 μm in the mold, which is otherwise trapped back in slag layer when EMS is off. Moreover, this effect diminishes with shifting the EMS down.