The Constitution and Kinetics of the System Fe-Mn-S Between 1200° and 1800°C

Abstract

<p>This thesis is concerned with the determination of the constitution of the ternary system Fe-Mn-S in the temperature range 1200° to 1600°C and the establishment of the kinetics of phase transformation (in the form of diffusion coefficients) within the system. Using the results of equilibration experiments and diffusion couple experiments, together with free energy composition diagrams, a solubility theory based on the Gibbs-Duhem equation, and data from the literature, the Fe-Mn-S phase diagram is constructed and presented as a compendium of isotherms. The significance of the phase diagram, as related to commercial steels, is discussed by investigating both quantitatively and qualitatively the quaternary effect of carbon on the ternary constitution in the region of the melting point of iron. Also discussed is sulfide inclusion formation and transformation during and after solidification.</p>