Numerical investigation on species transport in electroslag remelting dual alloy ingot

A transient three-dimensional (3D) comprehensive model has been developed to investigate the solute transport in electroslag remelting (ESR) dual alloy ingot. The solutions of the mass, momentum, energy, and species conservation equations were simultaneously calculated by the finite volume method, and full coupling of the Joule heating and Lorentz force through the solving Maxwell's equations. The movement of the metal droplet was described with the volume of fluid (VOF) approach. Besides, the solidification was modeled by using an enthalpy-based technique, where the mushy zone was treated as a porous medium with an anisotropic permeability. A reasonable agreement between the simulation and the experiment was obtained. The results indicate that the colder metal flowing downward washes the solidification front in the process. The solute-poor metal in the pool displaces the solute-rich metal in the mush region. Meanwhile, the solute enrichment promotes the sinking of the liquid. The inward Lorentz force pushes the metal from the periphery to the bottom. The solutes are deposited at the pool bottom. The negative segregation occurs in the lower part and then rises to positive for the two elements. The maximal positive and negative segregation indexes of the carbon and nickel along the vertical centerline of the ESR dual alloy ingot are 0.38 and −0.19, and 0.15 and −0.02, respectively.