The results of experimental studies of the structure, phase composition, defective substructure and mechanisms of hardening of bainitic constructional steels are presented. The main method of investigation was the method of modern physical material science - translucent electron diffraction microscopy of thin foils. Particular attention is paid to the analysis of carbon redistribution, the evolution of carbide and defect subsystems under deformation by uniaxial compression.The book is intended for scientific and engineering workers of research and scientific institutes, factory laboratories specializing in the fields of condensed state physics, metal science and thermal processing of metals and alloys, and can be useful to teachers, graduate students and university students of relevant specialties.