Thermodynamic analysis of sulfur in ESR steel din 14MOV63 using blast furnace slag

Sulphur behavior during electroslag refining of steel DIN 14MoV63 was thermodynamically analysed using the software Terra. Blast furnace slag was used as a flux additive. Blast furnace slag, contains 40…45 % SiO2; 40…42 % CaO; 10…12 % Al2O3; 8…9 % MgO и 1,5…2 % sulfur in the form of CaS. It is shown that metal desulphurization in the process of ESR occurs in the absence of CaS in the flux. However, that remelting under fluxes containing from 1 to 5 % of CaS leads to the transition of sulphur from slag to metal. Silicon and aluminium content in metal increases by 0.1…0.2 % and 0.001…0.002 %, respectively. An amount of CaS in slag decreases, whereas an amount of CaO increases. It was also discovered, that the distribution of sulphur along the height of the ingot is not uniform. Therefore, it is proposed to subject the blast furnace slag to preliminary desulfurization before its use as a flux additive in the ESR.