An algorithm is proposed for predicting the phase composition of titanium-containing steels after solidification. The approach is based on thermodynamic calculations and provides for crystallization through the formation of ferrite and austenite, as well as a peritectic reaction. The algorithm takes into account the possibility of precipitation of TiN, TiS, MnS and TiC0.5S0.5 from the liquid phase upon crystallization. Two possible behaviors of ferrite upon crystallization are considered: frozen and fast diffusion of elements in the metal sublattice of this phase. Calculations illustrating the operation of the proposed algorithm have been performed.