3D Numerical Simulation of the Var Consumable Electrode Melting Process
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3D Numerical Simulation of the Var Consumable Electrode Melting Process R. BHAR, A. JARDY, P. CHAPELLE, and V. DESCOTES A 3D numerical model was set up to simulate the formation and dynamics of the liquid metal film under the consumable electrode during VAR process. In the present paper, the implementation of this model is described. It was developed using the open source computational fluid dynamics (CFD) software OpenFOAM. The model solves coupled momentum and energy equations combined with a volume of fluid (VOF) method to track the liquid metal free surface. The melting of the electrode material is modeled with an enthalpy-porosity approach. The electric power supplied by the arc is supposed to be uniformly distributed over the surface of the electrode tip. For a given electric arc power, the model enables to quantitatively predict the dripping rate and hence the overall melt rate. Besides the thermal behavior of the electrode, simulation results illustrate the dynamics of the liquid film and the transfer mechanisms of the liquid metal during VAR melts performed with short and long interelectrode gaps. https://doi.org/10.1007/s11663-020-01966-x The Minerals, Metals & Materials Society and ASM International 2020
I.
INTRODUCTION
VACUUM arc remelting (VAR) is a secondary remelting process used to improve cleanliness as well as chemical and mechanical homogeneity of metal ingots. VAR was the first remelting process to be used commercially for superalloy processing. It is also typically the final stage in the melting cycle of reactive metals such as titanium and zirconium alloys.[1] The process consists of melting a consumable electrode under vacuum (see Figure 1). The heat source is a DC electric arc of low voltage and high current. The arc is created between the electrode (cathode) and the base plate of a water-cooled copper crucible at the beginning of the melt, then between the electrode and the secondary ingot (anode) forming in the crucible. The melting of the tip of the electrode generates a liquid metal film under the electrode, from which metal drops are produced that fall under the action of gravity into the crucible and progressively solidify to form the
R. BHAR is with the Institut Jean Lamour UMR CNRS 7198, LabEx DAMAS, UniversitO˜ de Lorraine, 2 allO˜e AndrO˜ Guinier, Campus Artem, 54011 Nancy Cedex, France and also with the Aperam Alloys Imphy Avenue Jean JaurO`s, BP-1, 58160 Imphy, France. A. JARDY and P. CHAPELLE are with the Institut Jean Lamour UMR CNRS 7198, LabEx DAMAS, UniversitO˜ de Lorraine. Contact email: [email protected] V. DESCOTES is with the Aperam Alloys Imphy Avenue Jean JaurO`s Manuscript submitted December 20, 2019.
METALLURGICAL AND MATERIALS TRANSACTIONS B
secondary ingot. At any instant, the ingot is composed of three zones: the fully solidified metal, the liquid pool fed by metal drops, and an intermediate mushy zone. The quality of the produced ingots strongly depends on the operating conditions of remelting. Among them, the melt rate and the interelectrode gap p
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