Abstract
Thermodynamic analysis of precipitation behaviors of Ti, Mn sulfide in hot-rolled steels, was conducted to evaluate the thermodynamic parameters of (Ti, Mn, Fe)S in steels.
Thermodynamic parameters of sulfide were assessed based on Q-phase (NaCl type): (Mn, Fe)S and P-phase (NiAs type): (Ti, Fe, Mn)S reported by Miettinen. Since it was found that P-phase and Q-phase coexisted, as distinct complex precipitates without changing their crystal structure even on the conditions which both P-phase and Q-phase precipitated at the same time. The thermodynamic parameters of these two phases were determined using the extraction data and TEM-EDS. The solubility limit of Fe and Mn to TiS, which causes errors in practical steels, was estimated by using the solubility product of TiS evaluated by Mitsui.
The calculated precipitation behaviors of Ti, Mn sulfide using developed thermodynamic parameter are in good agreement with the formation of sulfides and carbo-sulfides in hot rolled commercial IF steels.
