Abstract
Low-carbon aluminum-killed steels constitute the main group of structural steels produced in Russia and worldwide. These steels are used in the key sectors of the economy such as construction, automotive industry, mining and transportation of minerals. The steel melt deoxidation by aluminum leads to the formation of nonmetallic inclusions, which can significantly affect the quality of rolled products and reduce the manufacturability due to clogging of submerged entry nozzles, metering nozzles, and ladle sliding gates during the continuous casting. For example, steel contamination by nonmetallic inclusions may result in rejection due to surface defects, reduced yield of cast slabs, increased corrosion wear rates, defects detected by ultrasonic inspection, etc. Due to a particular shape, size and state of aggregation, nonmetallic inclusions based on aluminum deoxidation products are difficult to remove from the steel melt. An effective way to reduce the steel contamination of these inclusions is modifying their compositions to the liquid state of aggregation with calcium, which requires careful preparation of the molten slag and metal. The study describes in detail the main thermodynamic features of this process. Using an IF-steel example, the target range calculation of the calcium contents ensures the modification of the inclusions to the liquid state depending on the aluminum concentration in the steel melt. The limiting sulfur concentrations in the metal melt that prevent the formation of refractory sulfide shells on oxide nonmetallic inclusions have been calculated depending on the aluminum and calcium contents.
Similar content being viewed by others
REFERENCES
Zaitsev, A.I., Rodionova, I.G., Khoroshilov, A.D., Mezin, F.I., Semernin, G.V., Mishnev, P.A., Zhironkin, M.V., and Bikin, K.B., Analysis of surface defects occurrence in cold-rolled products from IF-steels, Elektrometallurgiya, 2012, no. 7, pp. 36–40.
Alalykin, N.V. and Khoroshilov, A.D., Improving the technology of melting and casting of IF-steel in the conditions of PJSC MMK, Materialy XV Mezhdunarodnogo kongressa staleplavil’shchikov (Proc. XV Int. Congr. of Steelmakers), Tula, 2018.
Zaitsev, A.I., Rodionova, I.G., Khoroshilov, A.D., Mezin, F.I., Semernin, G.V., Mishnev, P.A., Zhironkin, M.V., and Bikin, K.B., Optimization of end-to-end technology for producing continuously cast billets from IF-steels as an effective way to improve the surface quality of cold-rolled products, Elektrometallurgiya, 2012, no. 10, pp. 36–42.
Khoroshilov, A.D., Zaitsev, A.I., Rodionova, I.G., Yaburov, S.I., Mezin, F.I., Semernin, G.V., and Kazankov, A.Yu., Development of effective ways to reduce the sorting by surface defects of cold-rolled products from IF-steels, Chern. Metall., Byull. Nauchno-Tekh. Ekon. Inf., 2013, no. 7, pp. 38–41.
Riyahimalayeri, K., Ölund, P., and Selleby, M., Effect of vacuum degassing on non-metallic inclusions in an ASEA-SKF ladle furnace, Ironmaking Steelmaking, 2013, vol. 40, pp. 470–477.
Lind, M., Mechanism and kinetics of transformation of aluminia inclusions in steel by calcium treatment, PhD Thesis, Helsinki: Helsinki Univ. Technol. Press, 2006.
Sasi, K. and Mizukami Y., Mechanism of alumina adhesion to continuous caster nozzle with reoxidation of molten steel, ISIJ Int., 2001, vol. 41, no. 11, pp. 1331–1339.
Shakhpazov, E.Kh., Zaitsev, A.I., Shaposhnikov, N.G., Rodionova, I.G., and Rybkin, N.A., Physicochemical prediction of the types of nonmetallic inclusions: Complex deoxidation of steel with aluminum and calcium, Russ. Metall. (Engl. Transl.), 2006, vol. 2006, no. 2, pp. 99–107.
Zhang, L., Thomas, B.G., et al., Inclusion investigation during clean steel production at Baosteel, Proc. Conf. ISSTech 2003, Indianapolis, IN, April 27–30,2003, Warrendale, PA: Iron Steel Soc., 2003, pp. 141–156.
Holappa, L., Hämäläinen, M., Liukkonen, M., and Lind, M., Thermodynamic examination on inclusion modification and precipitation from calcium treatment to solidified steel, Ironmaking Steelmaking, 2003, vol. 30, no. 2, pp. 111–115.
Kimura, T. and Suito, H., Calcium deoxidation equilibrium in liquid iron, Metall. Mater. Trans. B, 1994, vol. 28, pp. 33–42.
Zaitsev, A.I., Mogutnov, B.M., and Shakhpazov, E.Kh., Fizicheskaya khimiya metallurgicheskikh rasplavov (Physical Chemistry of Metallurgical Melts), Moscow: Nauka, 2008.
Shornikov, S.I., Thermodynamic properties of the melts of CaO–Al2O3 system, Vestn. Otd. Nauk Zemle, Ross. Akad. Nauk, 2003, no. 1 (21), pp. 1–3.
Grigoryan, V.A., Stomakhin, A.Ya., Utochkin, Yu.I., Ponomarenko, A.G., Belyanchikov, L.N., Kotel’nikov, G.I., and Ostrovskii, O.I., Fiziko-khimicheskie raschety elektrostaleplavil’nykh protsessov (Physicochemical Calculations of Steelmaking Processes), Moscow: Mosk. Inst. Stali Splavov, 2007.
Yang, W., Cao, J., Wang, X.-H., et al., Investigation on non-metallic inclusions in LCAK steel produced by BOF‑LF-FTSC production route, J. Iron Steel Res. Int., 2011, vol. 18, no. 9, pp. 6–12.
Ye, G.-Z., Jonsson, P., and Lund, T., Thermodynamics and kinetics of the modification of A12O3 inclusions, ISIJ Int., 1996, vol. 36, suppl., pp. S105–S108.
Nita, P.S., Butnariu, I., and Constantin, N., The efficiency at industrial scale of a thermodynamic model for desulphurization of aluminum killed steels using slags in the system CaO–MgO–Al2O3–SiO2, Rev. Metal., 2010, vol. 46, no. 1, pp. 5–14.
Story, S.R., Piccone, T.J., Fruehan, R.J., and Potter, M., Inclusion analysis to predict casting behavior, Proc. Conf. ISSTech 2003, Indianapolis, IN, April 27–30, 2003, Warrendale, PA: Iron Steel Soc., 2003.
Tundish technology for clean steel production, World Scientific. 2007. http://www.worldscibooks.com/engineering/6426.html.
Björklund, J., A study of slag-steel-inclusion interaction during ladle treatment, Licentiate Thesis, Stockholm: R. Inst. Technol., 2006.
Author information
Authors and Affiliations
Corresponding author
Additional information
Translated by O. Lotova
About this article
Cite this article
Khoroshilov, A.D., Grigorovich, K.V. Thermodynamic Modification Aspects by Calcium of Nonmetallic Inclusions in Low-Carbon Aluminum-Killed Steels. Steel Transl. 49, 738–746 (2019). https://doi.org/10.3103/S0967091219110068
Received:
Revised:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.3103/S0967091219110068