The article covers the plotting of a mathematical model of thermal processes in materials under the influence of intense energy flows. The model is based on the nonlinear equation of heat conductivity. Chemical-thermal processes during laser treatment of steel are considered. The dismemberment method is used to solve nonlinear problems. Calculations of internal and external temperature stresses in a steel shaft under laser action are performed. For the first time, the influence of kinetically conditioned plastic deformation resulting from phase transformations in steel parts was considered in the theoretical analysis of the processes of formation of hardening stresses. It is assumed that the proposed method will allow solving important theoretical and practical problems in the field of chemical-thermal treatment of metals.