Multi-physics coupling model–based numerical analysis of the effect of the electric current path on electroslag remelting

Abstract

A multi-physics coupling model is developed to study the effect of the electric current path on the electroslag remelting (ESR) process. The electromagnetic field is calculated in the whole system including the molten slag, solidified slag, ingot and mold by the finite element method (FEM), while the two-phase flow, heat transfer, and solidification/melting are simultaneously solved using the finite volume method (FVM). The electrode melting rate is evaluated considering the actual heat flux from the slag to the electrode. Three electric current paths on an industrial scale ESR process are predicted after the experimental verification. When the current conductive mold (CCM) is used, approximately 73.7% of the total current entering the mold directly from the slag layer, wihle the skin effect disappers. The total Joule heat is 12.55 kW lower than that in the typical ESR system, causing a reduction of 7.4% in metal pool depth. When the slag skin is assumed to perfectly insulate the slag and ingot from the mold, the total Joule heating, electrode melting rate, and metal pool depth are overestimated. The insulation hypothesis must be used with great caution. Additionally, the effects of the fill ratio and slag height on the heat balance and metal pool profile in the ESR-CCM system are analyzed. The development of the model and the findings can help understand the industrial ESR processes with CCM and optimise the process design and operational parameters.