EVRAZ Nizhniy Tagil Iron & Steel Works (EVRAZ NTMK) (Nizhniy Tagil, Russia):

Kushnarev A. V., Cand. Eng., Managing Director, e-mail: director@ntmk.ru

Investigation of crack forming and propagation in the continuously cast billet axial area has been undertaken on the example of 430 mm diameter billet for consequent wheel forging. It is shown that initial length of axial cracks made 30–100 mm. Temperature casting speed eff ect on steel microstructure has been examined. The ways of lowering of rejects of railroad wheels due to non-metallic inclusions in a wheel rim are analyzed. Importance of permanent usage of ultrasonic control for quality checking of railroad wheels and tires is underlined and statistical data of wheel quality improvement since 1999 is presented (part of rejects decreased from 1.46% to 0.15%). Technical solutions for lowering of steel secondary oxidation at continuous casting machines are observed; they are based on providing reliable steel protection during continuous casting, sealing of metal casting routes and using special adapters (silver funnels), what has led to lowering of nitrogen content in steel by two times comparing with argon usage. Mastering of the continuous casting technology of wheel steel has been accompanied by solving of a row of technological problems in order to provide dense billet microstructure and lack of porosity and micro-cracks in the billet axial area, rational correlation between volume and stretching of structural areas of equiaxial crystals and columnar dendrites, as well as to eliminate causes of forming of clusters of non-metallic inclusions in the wheel rim and to prevent growing of secondary gas re-pickup at continuous casting machines.

1. Bogatov A. A. Mekhanicheskie svoystva i modeli razrusheniya metalla (Mechanical properties and models of metal destruction). Ekaterinburg : Ural State Technical University — Ural Polytechnical Institute, 2002. 328 p.
2. Kushnarev A. V., Kirichkov A. A., Petrenko A. A. et al. Sovershenstvovanie tekhnologii obrabotki metalla na ustanovke desulfuratsii v usloviyakh Otkrytogo Aktsionernogo Obshchestva “NTMK” (Improvement of metal processing technology on desulphurization unit in the conditions of “Nizhniy Tagil Iron and Steel Works” JSC). X Mezhdunarodnyy simpozium po desulfuratsii chuguna i stali (The X International Symposium on desulphuration of cast iron and steel). Almamet, 2011. pp. 55–62.
3. Kushnarev A. V., Smirnov L. A., Mukhatdinov N. Kh. et al. Osvoenie tekhnologii vyplavki stali iz uglerodistogo poluprodukta v konverterakh s kombinirovannoy produvkoy (Mastering of technology of steel smelting from carbonaceous semi-finished product in combined blowing converters). Trudy X Mezhdunarodnogo kongressa staleplavilshchikov, Magnitogorsk, 13–17 oktyabrya, 2008 (Proceedings of the X International congress of steel makers, Magnitogorsk, October 13–17, 2008). Moscow, 2009. pp. 130–132.
4. Kushnarev A. V., Ilin V. I., Shekhovtsov E. V. et al. Stal — Steel in Translation. 2003. No. 6. pp. 14–16.
5. Kushnarev A. V. Stal — Steel in Translation. 2013. No. 9. pp. 29–31.
6. Tretyakov M. A., Arshanskiy M. I. Chernaya metallurgiya. Byulleten nauchno-tekhnicheskoy informatsii — Ferrous metallurgy. Bulletin of scientific and technical information. 2010. No. 4. pp. 36–37.