Modeling of Solubility Product of TiN in Ti-Microalloyed Steels

Most carbonitride solubility products of Ti do not consider the influence of commonly contained alloying elements such as Mn and Si in predicting the dissolution law of carbonitrides in steels, which would cause a deviation between the experimental data and predicted values. To solve this problem, the solubility product models of TiN and TiC in austenite considering the influence of Mn, Mo, Cr, Si, and Al are established in the present study based on the two-sublattice model and relevant thermodynamic data. Different austenitizing temperatures are designed to analyze the precipitation law of the precipitates of a C–Si–Mn–Al–Mo–Ti–N steel. The experimental results show that the complete solution temperature of TiC is consistent with the calculation results of the TiC solubility product model. Due to the similar method establishing the TiC solubility product model, it is reasonably inferred that the predicting accuracy by the TiN solubility product model can be ensured. Additionally, as the austenitizing temperature increases, TiC particles completely dissolve between 1050 and 1100 °C, and then TiN particles begin to ripen when the temperature exceeds 1200 °C.