Effect of dynamic formation of multiphase slag skin on heat transfer and magneto-hydrodynamic flow in electroslag remelting process

During the electroslag remelting (ESR) process, the effect of dynamic formation of slag skin on magneto-hydrodynamic multiphase flow and temperature field is studied using a 2-D axisymmetric model. The electromagnetic field is described by user-defined functions. The dynamic formation and distribution of multiphase slag skin, as well as the interface between slag and metal, are investigated by using the volume of fluid (VOF) model and the dynamic meshing method. Especially, the effect of slag skin/air gap on heat transfer characteristics is considered and developed by user-defined functions. The results show that the thickness of slag skin at the interface between slag and metal increases as the axial distance from free surface of slag rises, reaching a maximum of about 25 mm. With the height of ingot increasing, the thickness of slag skin drops to 17 mm. When the current changes from 2.0 kA to 3.0 KA in the ESR process, the current density, Joule heat, velocity and temperature increases. In the meanwhile, the slag skin becomes thinner and the melt pool becomes deeper. The vibration of electrode has a weak effect on the formation behavior of slag skin, and only has effects on formation of metal droplet and velocity field.