A mathematical physical-based semi-empirical model and a corresponding computer program are developed for describing recrystallization process and carbonitrides particles precipitation in deformed austenite. The model is suitable for alloyed steels of a wide range of compositions. The model allows calculate a thermodynamic equilibrium for excess carbonitride phases with solid solution, the kinetics of their nucleation and growth, and their effect on recovery and recrystallization. A detailed description is given for each aspect of the model and its physical nature. Verification of the simulation results with the experimental data from published sources confirms the sufficient reliability of the proposed computer model for evaluative calculations. The model’s features are demonstrated by an example that simulates influence of Nb content on recristallization, recovery and nucleation, growth and Ostwald ripening of Nb and Ti carbonitride particles. The simulation shows and allows numerically evaluate the effect of slowing down recrystallization and recovery with increasing in Nb content. This indicates a significant effect of dispersed carbonitrides on recrystallization and recovery. The simulation theoretically predicts an intensification of Ti(C, N) particles precipitation and growth with an increase in the Nb concentration. Another result is an increase of dispersion and number of Nb(C, N) particles with an increase in the Nb concentration owing to more rapid transition to the Ostwald ripening stage, which is characterized by much more slowly average particle size growth than from a supersaturated solid solution.