Magnetohydrodynamic and Electrochemical Phenomena in Remelting Processes

In order to decrease CO2 production, the developments of a new generation of metallurgical processes using electric currents are planned by the world leading industrial groups. Strong currents will be transferred through plasma and high temperature electrolytes to achieve the production of new metallic alloys. The fundamental knowledge built by our research has the potential to solve complex physical, technical, and design issues that can arise during these crucial developments.

From daily experience, we know that. with a strong electric current, materials can be heated and even melted. However, when applied on an industrial scale, the fact that most materials are opaque causes a major problem because important details on what happens remain hidden. Here, the numerical process simulation acts as visualiser and allows to zoom-in when necessary. Even simulations with hypothetic properties or unusual process conditions can be done and thus hints in which direction a process optimisation might be possible can be gained. As an example, we have worked on understanding and optimising the Electro-slag remelting (ESR) process. This is a process where an extremely high electric current heats a liquid slag that then melts an electrode so that the alloy is then drop-wise crossing the liquid slag and forming a new liquid pool that finally solidifies with an improved quality.

The corresponding aims and objectives of this research field are:

  • to understand the interaction between phase distribution and magnetohydrodynamics when strong electric currents are applied;
  • to predict the electrical current path in the presence of strong spatial and temporal variation of electric conductivity;
  • to solve process instabilities and predict the formation of defects in the electroslag remelting process (ESR) and vacuum arc remelting (VAR) process;
  • to understand electrochemical aspects of the ESR process;
  • to predict the thermal and solidification characteristics during remelting of different metallic alloys;
  • to explore the origin of the coherent arc behaviour in the VAR process;
  • building a numerical model to predict the behaviour of an electric arc inside a furnace accounting for magnetohydrodynamics, flow dynamics, compressibility, turbulence and thermal fields.

Examples of recent achievements are given in Fig. 3. Further details on that research field can be found in

  • E. Karimi-Sibaki, A. Kharicha, J. Bohacek, M. Wu, A. Ludwig: “A Parametric Study of the Vacuum Arc Remelting (VAR) Process: Effects of Arc Radius, Side Arcing, and Gas Cooling”, Metall. Mater. Trans. (2019) 1-14.
  • E. Karimi-Sibaki, A. Kharicha, J. Bohacek, M. Wu, A. Ludwig: “Contribution of an Electro-Vortex Flow to Primary, Secondary, and Tertiary Electric Cur- rent Distribution in an Electrolyte”, J. Electrochem. Soc. 165 (2018) E604-15
  • E. Karimi-Sibaki, A. Kharicha, M. Wu, A. Ludwig, J. Bohacek: “Confrontation of the Ohmic approach with the ionic transport approach for modeling the electrical behavior of an electrolyte”, Ionics 24 (2018) 2157–65.
  • E. Karimi-Sibaki, A. Kharicha, M. Wu, A. Ludwig, J. Bohacek: “Modeling electrochemical transport of ions in the molten CaF2 –FeO slag operating under a DC voltage”, Appl. Math. Comput. 357 (2018) 357-73.
  • A. Kharicha, E. Karimi-Sibaki, M. Wu, A. Ludwig, J. Bohacek: “Review on Modeling and Simulation of Electroslag Remelting”, Steel Res. Int. 89 (2018) 1700100:1-20.
  • E. Karimi-Sibaki, A. Kharicha, M. Wu, A. Ludwig, J. Bohacek: “Toward Modeling of Electrochemical Reactions during Electroslag Remelting (ESR) Process”, Steel Res. Int. 88 (2017) 1700011:1-8.
  • A. Kharicha, M. Wu, A. Ludwig, E. Karimi-Sibaki: “Simulation of the Electrical Signal During the Formation and Departure of Droplets in the Electro Slag Remelting Process”, Metall. Mater. Trans. B 47 (2016) 1427-34.
  • E. Karimi-Sibaki, A. Kharicha, J. Bohacek, M. Wu, A. Ludwig: “On Validity of Axisymmetric Assumption for Modeling an Industrial Scale Electroslag Remelting Process”, Adv. Eng. Mater. 18 (2016) 224-30.
  • E. Karimi-Sibaki, A. Kharicha, J. Bohacek, M. Wu, A. Ludwig: “A Dynamic Mesh-Based Approach to Model Melting and Shape of an ESR Electrode”, Metall. Mater. Trans. 46 (2015) 4854-67.

see also our Topic Related Publications