Experimental design and the finite element method were used for the simulation of dynamic and static recrystallization and mechanical properties of steels under hot rolling and high-temperature thermomechanical treatment conditions. It is proposed that a recrystallization diagram of a special type could be used for the quantitative estimation of dynamic and static recrystallization development. The latter depends on the main high temperature thermomechanical treatment parameters: deformation temperature, strain and elapsed time followed by the end of deformation up to the start of accelerated cooling. It was found that mechanical properties changes correspond to recrystallization changes. Mathematical models and nomographs of recrystallization fraction and yield strength dependences from above mentioned parameters were obtained. The study results demonstrate the possibilities to use such type of recrystallization diagrams and the finite element method modeling simulation to predict structure and mechanical properties for different cross-sections of rolled billets and parts.