Impact of the Solidified Slag Skin on the Current Distribution During Electroslag Remelting

The ESR process is commonly used to produce defect-free ingots of high added value alloys such as special steels or Ni-based superalloys. Numerous simulation tools have been developed for the last 30 years to get better insight into the process and help its optimization. Most assume that no electrical current is able to cross the solidified slag skin and flow in the water-cooled mold. However, it has recently been claimed that the slag skin does not ensure perfect insulation, which is prone to modify the current distribution, hence some of the results previously assessed. This paper presents the assumptions made to simulate that phenomenon and some results in terms of current flow into the mold, depending on the thickness and electrical conductivity of the solidified slag skin. Results show that both parameters can have a great influence on the current distribution, hence the slag behaviour and final ingot quality.