A Review on Sulphur Thermodynamics in Liquid Iron

Abstract Sulphur in steel, primarily introduced during ironmaking through coke, forms sulphide non-metallic inclusions, which adversely affect hot working processes and steel properties, reducing impact toughness, ductility, weldability, and corrosion resistance. To mitigate these effects, desulphurisation techniques remove sulphur by forming stable sulphides in the slag phase, primarily through ladle slag treatment. Understanding sulphur thermodynamics in liquid iron is essential for controlling its solubility and activity during steelmaking. This study reviews existing methods for determining sulphur solubility in iron melts, highlighting challenges due to its high solubility and complex phase interactions. It also examines element-sulphur reactions and the conditions for sulphide formation. Overall, this work provides a comprehensive analysis of sulphur’s role in steel metallurgy and offers insights to optimise desulphurisation practices for improved steel quality.