Thermodynamic analysis of the reduction of pipe steel

Abstract

In thermodynamic calculations, the activity of oxygen in equilibrium with Al, Mn, and Ce is determined for four melts of pipe steel. Pure gaseous oxygen under pressure is adopted as the standard state of oxygen dissolved in liquid metal. The actual (above-equilibrium) activity of oxygen is calculated on the basis of electrochemical measurements in liquid steel by oxygen sensors. For the melts, the difference between the actual and equilibrium chemical potentials, which may be regarded as the factor that drives reduction, is 14–20 kJ/mol. The conditions for microalloying of the melt with cerium are assessed.