Results of investigations of a structure formation at every stage of heat and thermomechanical treatments are given and generalized, laws of hereditary influence of both initial structure and conditions of heating and deformation on a formation kinetics, morphology, and substructure of the martensite in steels of various compositions are determined. The information about mechanisms and kinetics of all processes is systematized, conditions of stabilization or of acceleration of the martensite decomposition, carbide formation processes, and softening under the annealing and repeated austenitization are determined.