Evaluating oxygen level of Si-deoxidized H13 die steel using ferrous oxide-containing slags at 1873 K

Laboratory-scale experiments were conducted to investigate the oxygen content of Si-deoxidized H13 die steel by ferrous oxide-containing slags at 1873 K. The calculation of thermodynamics and kinetics was performed to evaluate the oxygen level of molten steel through [Si]–[O] equilibrium and [Fe]–[O] equilibrium. The results show that as the FeO content in slag increases, the oxygen content with [Si]–[O] equilibrium (w([O])_Si) has almost no change. When both the oxygen content with [Fe]–[O] equilibrium (w([O])_Fe) and w([O])_Si are less than the initial oxygen content in steel (w(TO)_i), the oxygen content in steel (w([O])) depends on the higher value between w([O])_Si and w([O])_Fe. In the case of w([O])_Fe > w(TO)_i, the value of w([O]) is the difference between the sum of w(TO)_i and w([O])_Si and the value of w([O])_Fe. The reaction rates of [Si]–[O] and [Fe]–[O] are equal, which are controlled by the mass transfer of oxygen in molten steel. The evaluation method is suitable to the whole smelting process of Si-deoxidized H13 die steel.