In the present paper a numerical model is developed to predict the exact electric current paths in the slag region of an Electro‐Slag‐Remelting (ESR) process. The model solves the momentum and energy equations. The solidification of the slag at the mould is modelled with an enthalpy‐porosity approach. The magnitude of the Joule heating and the Lorentz force are derived from the computed electric current lines. The localization where the Joule heating occurs controls the temperature distribution. The electric current distribution is in turn influenced by the temperature field through the temperature dependant electric conductivity. With this numerical tool the electric current paths are exactly computed by choosing the less resistive way to the liquid pool, or to the mould. For a given electric intensity the model predicts the power generated by the system and the solidified slag thickness at the mould. The model is validated by comparing its results with experiments on a small scale ESR process with high current density.

Numerical simulation of vacuum arc re-melting, pressurized or protective electro-slag re-melting, and ingot casting have become quite important in the metal industry. However, a major drawback of these simulation techniques is the lack of accurate thermophysical properties for temperatures above 1,500 K. Heat capacity, heat of fusion, density, and thermal conductivity are important input parameters for the heat transfer equation. Since, direct measurements of thermal conductivity of alloys in the liquid state are almost impossible, its estimation from electrical conductivity using the Wiedemann-Franz law is very useful. The afore-mentioned thermophysical properties of several steels are investigated within the context of an ongoing project. Here, we present a full set of thermophysical data for the chromium-nickel-molybdenum steel meeting the standard DIN 1.4435 (X2CrNiMo18-14-3); these values will be used by our partner to simulate various re-melting and solidification processes. Wire-shaped samples of the steel are resistively volume-heated, as part of a fast capacitor discharge circuit. Time-resolved measurements with sub-µs resolution of current through the specimen are performed with a Pearson probe. The voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers, the temperature of the sample with a pyrometer, and the volumetric expansion of the wire with a fast acting CCD camera. These measurements enable the heat of fusion, the heat capacity, and the electrical resistivity to be determined as a function of temperature in the solid and liquid phases. The thermal conductivity and thermal diffusivity are estimated via the Wiedemann-Franz law.

Strong temperature fluctuations might exist in non-isothermal turbulent flow. When a RANS approach is used for simulation it is necessary to time average all properties that are temperature dependant. Here we focus on the time average of the Joule heating released within the turbulent slag region of an electroslag remelting process (ESR). For that the average temperature dependant electric conductivity of the slag was expressed as a function of the time averaged temperature field and its standard deviation. The results using this new approach are compared with the results given by the classical approach using only the electric conductivity at the time averaged temperature. It will be shown that the temperature fluctuations decrease strongly the amount of electric current flowing directly to the mould, and increase the efficiency of the remelting process by 50%.

A multiphase approach is used to study macrosegregation phenomena that occur during solidification of steel ingot castings. The goal is to enhance the understanding of different mechanisms of macrosegregation formation. 4 different cases are presented consecutively with increasing complexity of the model assumptions and increasing dimensions: (1) feeding-induced macrosegregations in 1-dimentional unidirectional solidification situation, (2) macrosegregations caused by thermosolutal buoyancy driven flow in a 2-dimensional axially symmetric benchmark ingot, (3) macrosegregations caused by grain sedimentation in the same 2-dimensional ingot, and (4) macrosegregations which form during mixed equiaxed-columnar solidification in a full 3-dimensional benchmark ingot.

The Electro-Slag-Remelting (ESR) is an advanced technology for the production of components of e.g. high quality steels. In the present study a comprehensive computational model using the VOF technique for the prediction of the slag/pool interface is presented for axisymmetric and steady state conditions. In this model the distribution of the electric current is not constant in time, but is dynamically computed according to the evolution of the slag and steel phase distribution. The turbulent flow, created by the Lorentz and buoyancy forces, is computed by solving the time-averaged mass and momentum conservation equations. The turbulence effect is modelled by using a k-model. Two numerical simulations were performed, one assuming a flat interface, and a second leaving the interface free to find an equilibrium shape. The results are then analysed and compared for both cases.