Transfer of Oxygen and Sulfur during Direct Current Electroslag Remelting

Behaviors of oxygen and sulfur during DC ESR were investigated to treat their transfer on wide operating scales. On oxygen transfer, a carbon steel was remelted in CaF2-Al2O3 slag under the atmosphere. It was confirmed that ingots remelted as electrodes of negative polarity give higher oxygen content than those as positive. Those differences would be resulted from the differences of the current density and the interfacial area between the metal and the slag. The oxygen contents in the ingots remelted in a large scale furnace could be estimated from the present results on the oxygen transfer through the molten metal/slag interface, assuming that the mass transfer coefficient of oxygen depends on the current density of the interface. On sulfur transfer, a resulfurized carbon steel was remelted in ANF-6 and ANF-7 slaps under the atmospheres of varied oxygen partial pressure. Assuming the electrochemical reactions at the reacting interfaces, the accumulating rate of sulfur in the slag pool was determined. And then the sulfur in the ingot was calculated on the mass balance of sulfur. The calculated results were compared with the experimental ones. On DCSP, the calculated results show the good agreement with the experimental ones, but not on DCRP.