Siberian State Industrial University (Novokuznetsk, Russia):

Gromov V. E., Dr. Phys.-Math., Prof., Head of Chair of Physics,  gromov@physics.sibsiu.ru
Konovalov S. V., Cand. Eng., Ass. Prof., Chair of Physics

Institute of High-Current Electronics (Tomsk, Russia):
Ivanov Yu. F., Dr. Phys.-Math., Prof.

EVRAZ — United West Siberian Metallurgical Works (Novokuznetsk, Russia):
Kosterev V. B., Cand. Eng., Engineer
Efimov O. Yu., Cand. Eng., Chief Engineer
Yuryev A. B., Dr. Eng., Managing Director

The results of investigations of physical nature of thermomechanical strengthening of 09G2S steel (0.1% C, 1% Mn, 2% Si) for H-beam are presented. Materials and methods of investigation are observed: optical microscope “Axiovert 40MAT” with 100 and 500 amplification and electronic microscope EM-125 with 8,000–80,000 amplification for structure investigation, PMT-3 device for testing of micro-hardness. The quantitative regularities of structure, phase composition, defect substructure and mechanical properties formation in different H-beam cross sections under accelerated cooling in different regimes are established. Analysis of physical mechanisms has been conducted on the base of usage of quantitative parameters of steel structure; these mechanisms are responsible for increase of microhardness of surfacial layer during thermomechanical strengthe ning. Quantitative parameters characterizing structural and phase state and allowing to estimate value of theoretical yield strength of steel are revealed. It is shown that state of defect substructure of α-phase is determined by the mechanism of γ-α transformation, by conditions of high-temperature rolling and accelerated cooling and by distance to the surface of accelerated cooling. The gradient structure-phase states formation being characterized by the regular change of dislocation substructure types and parameters, average cementite particles sizes and nano-sized range α-phase fragments on cross section are revealed by methods of transmission electron diffraction microscopy. It is established that substructure and deformation mechanisms depended on martensite and bainite formation are the main responsible reasons for the hardened layer strength increase.

1. Ivanov Yu. F., Kovalenko V. V., Kozlov E. V., Gromov V. E. et al. Gradientnye strukturno-fazovye sostoyaniya v stalyakh (Gradient structural and phase conditions in steels). Novosibirsk : Nauka, 2006. 280 p.
2. Kovalenko V. V., Kozlov E. V., Ivanov Yu. F., Gromov V. E. et al. Fizicheskaya priroda formirovaniya i evolyutsii gradientnykh strukturno- fazovykh sostoyaniy v stalyakh i splavakh (Physical character of formation and evolution of gradient structural and phase conditions in steels and alloys). Novokuznetsk : “Poligrafist” LLC, 2009. 557 p.
3. Kosterev V. B., Belov E. G., Efimov O. Yu. et al. Vestnik Tambovskogo universiteta — Bulletin of Tambov University. 2010. Vol 15, Iss. 3. pp. 825–826.
4. Kosterev V. B., Gromov V. E., Ivanov Yu. F. et al. Deformatsiya i Razrushenie Materialov — Deformation and Fracture of Materials. 2010. No. 10. pp. 43–46.
5. Efimov O. Yu., Kosterev V. B., Gromov V. E. et al. Problemy chernoy metallurgii i materialovedeniya — Problems of ferrous metallurgy and materials science. 2010. No. 3. pp. 13–21.
6. Gromov V. E., Ivanov Yu. F., Efimov O. Yu. et al. Materialovedenie — Inorganic Materials: Applied Research. 2011. No. 1. pp. 40–42. 

7. Kosterev V. B., Gromov V. E., Ivanov Yu. F. et al. Zagotovitelnye proizvodstva v mashinostroenii — Procurement productions in mechanical engineering. 2011. No. 1. pp. 38–42.
8. Gromov V. E., Ivanov Yu. F., Kosterev V. B. et al. Strukturno-fazovye sostoyaniya i defektnaya substruktura termomekhanicheski uprochnennoy malouglerodistoy stali (Structural and phase conditions and defective substructure of thermo mechanically strengthened low-carbon steel). Novokuznetsk : Inter-Kuzbass, 2011. 166 p.