A Comprehensive Model of the Electroslag Remelting Process: Description and Validation

Abstract

Electroslag remelting (ESR) is widely used for the production of high-value-added alloys such as special steels or nickel-based superalloys. Because of high trial costs and the complexity of the mechanisms involved, trial-and-error-based approaches are not well suited for fundamental studies or for optimization of the process. Consequently, a transient-state numerical model has been developed that accounts for electromagnetic phenomena and coupled heat and momentum transfers in an axisymmetrical geometry. The model simulates the continuous growth of the electroslag-remelted ingot through a mesh-splitting method. In addition, solidification of the metal is modeled by an enthalpy-based technique. A turbulence model is implemented to compute the motion of liquid phases (slag and metal), while the mushy zone is described as a porous medium the permeability of which varies with the liquid fraction, thus enabling accurate calculation of solid/liquid interaction. The coupled partial differential equations (PDEs) are solved using a finite-volume technique. The computed results are compared to the experimental observation of an industrial remelted ingot; the melt pool depth and shape, in particular, are investigated, in order to validate the model. These results provide valuable information about the process performance and the influence of the operating parameters. In this way, we present an example of a model used as a support in analyzing the influence of the electrode fill ratio.

Numerical Investigation on the Effect of Slag Thickness on Metal Pool Profile in Electroslag Remelting Process

“…[6][7][8][9] Weber et al simulated the remelting of a nickel-based alloy by a two-dimensional axisymmetric model. 10) The computed results matched well with experimental data. The model was then used to study the influence of the fill ration on the ESR process.…”

Effect of Slag Composition on the Oxidation Kinetics of Alloying Elements during Electroslag Remelting of Stainless Steel: Part-1 Mass-transfer Model

“…Electroslag remelting (ESR) is employed for producing special steels and alloys in consideration of its exclusively outstanding advantages, 1,2) such as effective removal of non-metallic inclusions, homogeneous composition and excellent solidification structure of final products. With the requirement for homogeneity of chemical composition along the height of ingot becoming increasingly strict, the details of the processes controlling solute redistribution base on mass transfer model should be understood quantitatively to lower the cost of experiment.…”

The Structural Evolution and Segregation in a Dual Alloy Ingot Processed by Electroslag Remelting

“…In addition, the density of C (ρC = 1800 kg/m 3 ) and Cr (ρCr = 6900 kg/m 3 ) is lower than that of iron (ρFe = 7500 kg/m 3 ) [15], resulting in the so-called gravity segregation, with higher Cr and C contents in the liquid. Due to the clockwise circular flow at the solidification front, …”

“…The solute elements Ni, Cr, and C become enriched in the mushy zone in Ni, Cr, and C because of their partition ratios (k Ni = 0.94, k Cr = 0.76, and k C = 0.34) [14] between solid and remained liquid alloy, which are less than 1. In addition, the density of C (ρ C = 1800 kg/m 3 ) and Cr (ρ Cr = 6900 kg/m 3 ) is lower than that of iron (ρ Fe = 7500 kg/m 3 ) [15], resulting in the so-called gravity segregation, with higher Cr and C contents in the liquid. Due to the clockwise circular flow at the solidification front, the solute-poor (Ni, Cr, and C) metal in the pool displaces the solute-rich metal through washing the mushy region.…”