Kurgan State University (Kurgan, Russia):

Gurevich Yu. G., Dr. Eng., Prof. of the Chair “Power Engineering and metals Technology”, e-mail: ygg@rambler.ru

Microstructure of films forming on the surface of liquid steel at different temperatures was investigated. Pilot melts have been produced in 30-kg high-frequency furnace with magnesite crucible. Charge material consisted of the same initial materials: soft iron, metallic chromium, ferromanganese, 75% ferrosilicon, nickel and ferrotitanium. After complete titanium dissolution, metal was held du ring 5–10 min with consequent slag removal out of the furnace. The paper presents the results of investigation of microstructure of fi lms, forming on the surface of liquid steel Kh18N10T (Х18Н10Т) at diff e rent temperatures. It was revealed that crystallization of liquid steel is accompanied by inclusions of golden colour. Non-metallic inclusions that were electrolytically extracted from cast samples, have been subjected to petrographic analysis. This analysis displayed that the most part of inclusions is presented by titanium nitride crystals. Thermodynamical analysis of Fe–Ti–N system has confirmed that titanium nitrides can be extracted from liquid steel at titanium concentration ≤0.5% and at nitrogen concentration ≤0.08%. It was established experimentally that equilibrium of nitride extraction reaction from liquid steel can't be achieved and it is required to provide titanium content in steel ≥0.5% and nitrogen content ≥0.016% for coating of carbide lattice by titanium nitride.

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6. Gurevich K, Rotermel P., Savinjih L. The New Wear Resistant Composition Carbide — Pig Iron. Proceedings of the 2nd International conference. Tallin: Tallin Technical University, 2000. pp. 267–268
7. Gurevich Yu. G., Antsiferov V. N., Savinykh L. M. et al. Iznosostoykie kompozitsionnye materialy (Wear-resistance composite materials). Sverdlovsk : Ural Branch of Russian Academy of Sciences, 2005. 216 p.
8. Gurevich Yu. G., Narvy V. K., Frage N. R. Karbidostali (Carbidosteels). Moscow : Metallurgiya, 1988. p. 25.