A Comprehensive Model of the Electroslag Remelting Process: Description and Validation V. WEBER, A. JARDY, B. DUSSOUBS, D. ABLITZER, S. RYBE ´ RON, V. SCHMITT, S. HANS, and H. POISSON 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. DOI: 10.1007/s11663-008-9208-9 Ó The Minerals, Metals & Materials Society and ASM International 2009 I. INTRODUCTION ELECTROSLAG remelting (ESR) has been devel- oped to produce high-performance alloys dedicated to critical applications for which high-metallurgical-quality ingots are necessary. Consequently, primary melting is not sufficient; remelting, on the other hand, provides valuable advantages, such as a fine solidification struc- ture, limited occurrence of solidification defects, low levels of micro- and macrosegregation, and sound ingots. Moreover, insulation from air and chemical refining due to the presence of slag improve the inclusional quality. [1,2] An alternating current (AC) flows from a conventional ingot, also called an electrode, to a water-cooled baseplate through a high-resistivity calcium-fluoride-based slag, thus generating Joule heating. The energy is transferred both to the electrode for the melting and to the secondary ingot. Molten metal is produced in the form of droplets that fall in the water-cooled copper mold, building up the final solid ingot, as shown in Figure 1. Therefore, during remelting, the secondary ingot is composed of a liquid metal pool, a mushy zone, and a solid part. As noticed previously, additional chemical refining is obtained dur- ing the passage of the droplets through the slag. Electroslag-remelted products are high-value-added metallic alloys such as specialty steels or nickel-based superalloys. Consequently, trial-and-error approaches are very expensive and not well suited for systematic studies. Furthermore, the implementation of in-situ experiments is very complicated, due to high-temperature operating conditions. Mathematical modeling is, therefore, a valu- able tool for enhancing fundamental understanding, because it allows us to link the operating parameters, such as the melting rate, ingot diameter, and cooling parameters, to local solidification conditions and, thus, to the ingot final quality. For these reasons, a comprehensive model of the ESR process has been developed at the Laboratory of Science and Engineering of Materials and Metallurgy (LSG2M), located in the School of Mines at Nancy, France. The development started in 2004 with a basic hydrodynamic model of the slag. The model was improved step by step, using some former work carried out in Nancy. [3,4] Indeed, the model has several features in common with the SOLAR (Ecole des Mines, Nancy Cedex, France) code, [5–7] which simulates the vacuum arc remelting operation, because both processes are quite similar in terms of ingot growth and solidification. This article presents a two-dimensional axisymmetric transient model of the ESR process, which accounts for coupled electromagnetic, fluid flow, heat transfer, and phase-change phenomena. The purpose of this article is to expose and validate the results by comparing them V. WEBER, formerly Postdoctoral Student, LSG2M, Ecole des Mines de Nancy, Nancy Cedex 54042, France is Research Engineer, ArcelorMittal, Maizie`res-le`s-Metz 57283, France. A. JARDY, CNRS Research Scientist, B. DUSSOUBS, Research Engineer, and D. ABLITZER, Professor, are with the LSG2M, Ecole des Mines de Nancy, France. S. RYBE ´ RON, Development Technician, and V. SCHMITT, S. HANS, and H. POISSON, Development Engineers, are with Aubert & Duval, Les Ancizes 63770, France. Contact e-mail: alain.jardy@mines.inpl-nancy.fr This article is based on a presentation given at the International Symposium on Liquid Metal Processing and Casting (LMPC 2007), which occurred in September 2007 in Nancy, France. Article published online January 14, 2009. METALLURGICAL AND MATERIALS TRANSACTIONS B VOLUME 40B, JUNE 2009—271