Abstract-Evolution of phase state and defective substructure double-T iron made of 09G2S steel executed methods of transmission electron microscopy after thermo-mechanical strengthening. It is found out that as accelerated refrigeration approaches the surface gradient structure is formed in the material which is characterizes by regular parametric variation of dislocation substructure and midsized particles of cementite. Midsized particles of cementite and -phase fragments in the coating surface of the double-T iron correspond to nanostructural condition.