Analysis of the influence of electrode rotation on the desulfurization behavior during electroslag remelting process

Abstract

A transient multi-physics coupling mathematical model is developed to investigate the influence of electrode rotation on desulfurization in the electroslag remelting (ESR) process. This model incorporates a thermodynamic and kinetic model to calculate the sulfur transfer rate from steel to slag, while simultaneously including the magnetohydrodynamic flow, heat transfer, and species transport. The volume of fluid (VOF) approach is employed to track the slag-steel interface. Experimental validation is conducted to ensure the reliability of the model. Sulfur in steel is primarily removed at the slag-electrode interface and the slag-droplet interface, but the slag-metal pool interface contributes very little to desulfurization. The electrode rotation disperses the molten droplets and enhances the heat convection, resulting in a reduction of the total amount of Joule heat and the temperature within the mold. At the electrode tip, rotating the electrode achieves a higher removal of sulfur, more than 10 % compared to the static electrode. The final removal ratios of sulfur are 78.79 %, 82.01 %, 84.90 %, and 80.81 % with the electrode rotating at 0, 20, 40, and 60 rpm, respectively. The optimal desulfurization is achieved at the rotating speed of 40 rpm, due to the refined droplets, the faster renewal rate of the slag-steel interface, the elevated temperature of the interface, and the longer residence time for droplets passing through the slag layer.