Numerical Investigation About the Effect of Axial Static Magnetic Field on Improvement of Metal Pool Profile During Electroslag Remelting Process

A transient two-dimensional (2D) coupled mathematical model was developed to study the effect of external axial static magnetic field (ASMF) on the evolution of metal pool profiles. Electromagnetic flow, heat transfer, and solidification were explored simultaneously in this model. The growth of the ingot was predicted with the dynamic mesh technique. The calculated results indicated that the temperature distribution became more uniform both in slag and metal pool with 0.05-T ASMF. To characterize the metal pool profile more reasonable, the actual depth \(({H}_{\text{a}}={H}_{\text{m}}-{H}_{\text{c}})\) is defined to represent the depth of the metal pool. Compared with the case without applying ASMF, the calculated actual metal pool profile was flattened remarkably from 23 to 17.5 mm. Meanwhile, the calculated actual metal pool depth was compared with the measurement, which was from 25.5 to 16 mm, in experiments on a laboratory scale to validate the model. In addition, the mechanisms how ASMF improved the metal pool profile were elaborated thoroughly. Under the interaction of ASMF and the direct current component (DCC), the induced rotating Lorentz force makes the temperature field of slag pool more uniform. As a result, the heat transfer from slag to metal pool becomes more well distributed. On the other hand, the forced flow of metal pool by the drag of slag pool can enhance the effective thermal conductivity of metal pool and then reduce the temperature gradient in radial direction. All of above ultimately lead to a shallower metal pool.