Thermal behaviour of the consumable electrode in the vacuum arc remelting process

The thermal behaviour of the consumable electrode is studied using both experimental measurements and mathematical modelling. Infrared thermography measurements performed on an industrial furnace highlight qualitatively that the electrode height thermally affected by the electric arc is very small and depends on the melting rate. The vertical temperature gradient recorded at the base of the electrode varies between 350 K/cm and 650 K/cm, while the average measured superheat lies between 150 K and 200 K. A 2D mathematical model of the thermal behaviour of the consumable electrode during melting has been developed. Using the operating parameters as model inputs, it makes it possible to predict the melt rate and the evolution of the shape of the electrode base. The results of the model are successfully compared to melt rate experimental data obtained in a real VAR furnace. The thermal effect of cracks in the electrode is investigated and reveals a significant influence on the variation in melt rate. (C) 2009 Elsevier B.V. All rights reserved.