Electric current partition during vacuum arc remelting of steel: An experimental study

This paper describes measurements of the voltage and temperature profiles in a vacuum arc remelting (VAR) crucible during a series of melts of a 40CrMoV13-9 steel alloy electrode, which were used to obtain information about the current flows in the furnace. The results derived included the current leaving the crucible above the ingot crown, the current flowing between the crucible and the crown, the current transferred between the crucible and the ingot lateral surface and the current flowing through the ingot bottom. It was established that the crown (observed to be 5–10 cm high) played a predominant role in the current distribution, as the crown carried more than 50% of the furnace current. A small but non negligible fraction of the furnace current (about 10%), which represents the lower limit of the side-arcing current, was found to leave the crucible above the crown. The effect of the arc gap length on the current distribution was examined, but no general trend was clearly identified. Finally, a summary of the results reported in this study and those previously obtained in the literature is presented. Significant differences regarding the estimated amount of the side arcing current were noted that did not seem to be directly related to the changes in the remelted materials or melting conditions. It was pointed out that a detailed understanding of the current partition in the furnace requires additional experimental and theoretical study to clarify the path of the current flowing through the ingot crown.

► We investigate experimentally the current partition in a vacuum arc remelting furnace during the melt of a steel electrode.
► The ingot crown carries more than 50% of the furnace current.
► The side-arcing current leaving the crucible above the crown remains small (about 10% of the furnace current).
► No clear relation between the current partition and the variation of the gap length could be established.