Abstract
On the basis of the practical production of non-oriented silicon steel, the formation of MgO·Al2O3 inclusions was analyzed in the process of “basic oxygen furnace (BOF) → RH → compact strip production (CSP)”. The thermodynamic and kinetic conditions of the formation of MgO·Al2O3 inclusions were discussed, and the behavior of slag entrapment in molten steel during RH refining was simulated by computational fluid dynamics (CFD) software. The results showed that the MgO/Al2O3 mass ratio was in the range from 0.005 to 0.017 and that MgO·Al2O3 inclusions were not observed before the RH refining process. In contrast, the MgO/Al2O3 mass ratio was in the range from 0.30 to 0.50, and the percentage of MgO·Al2O3 spinel inclusions reached 58.4% of the total inclusions after the RH refining process. The compositions of the slag were similar to those of the inclusions; furthermore, the critical velocity of slag entrapment was calculated to be 0.45 m·s−1 at an argon flow rate of 698 L·min−1, as simulated using CFD software. When the test steel was in equilibrium with the slag, [Mg] was 0.00024wt%–0.00028wt% and [Al]s was 0.31wt%–0.37wt%; these concentrations were theoretically calculated to fall within the MgO·Al2O3 formation zone, thereby leading to the formation of MgO·Al2O3 inclusions in the steel. Thus, the formation of MgO·Al2O3 inclusions would be inhibited by reducing the quantity of slag entrapment, controlling the roughing slag during casting, and controlling the composition of the slag and the MgO content in the ladle refractory.
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References
Y.Q. Song, J.S. Li, J. Li, Z.F. Wang, and S.F. Yang, MgO·Al2O3 based inclusions in gas cylinder steel during refining, J. Univ. Sci. Technol. Beijing, 31(2009), Suppl. 1, p. 130.
J. Yang and X.H. Wang, Thermodynamics analysis and control of formation of magnesia-alumina spinel during refining of ultra-low oxygen, Iron Steel, 46(2011), No. 7, p. 26.
K. Beskow, N.N. Tripathi, M. Nzotta, A. Sandberg, and S.C. Du, Impact of slag refractory lining reactions on the formation of inclusions in steel, Ironmaking Steelmaking, 31(2004), No. 6, p. 321.
H. Itoh, M. Hino, and S. Banya, Thermodynamics on the formation of spinel nonmetallic inclusion in liquid steel, Metall. Mater. Trans. B, 28(1997), No. 5, p. 953.
J.H. Park and D.S. Kim, Effect of CaO-A12O3-MgO slags on the formation of MgO-A12O3 inclusions in ferritic stainless steel, Metall. Mater. Trans. B, 36(2005), No. 4, p. 495.
J.H. Park, Formation mechanism of spinel-type inclusions in high-alloyed stainless steel melts, Metall. Mater. Trans. B, 38(2007), No. 4, p. 657.
Y.J. Kang, F. Li, K. Morita, and S.C. Du, Mechanism study on the formation of liquid calcium aluminate inclusion from MgO-Al2O3 spinel, Steel Res. Int., 77(2006), No. 1, p.785.
C.W. Seo, S.H. Kim, S.K. Jo, M.O. Suk, and S.M. Byun, Modification and minimization of spinel (Al2O3·xMgO) inclusions formed in Ti-added steel melts, Metall. Mater. Trans. B, 41(2010), No. 4, p. 790.
M. Jiang, X.H. Wang, B. Chen, and W.J. Wang, Laboratory study on evolution mechanisms of non-metallic inclusions in high strength alloyed steel refined by high basicity slag, ISIJ Int., 50(2010), No. 1, p. 95.
M. Jiang, X.H. Wang, and W.J. Wang, Control of non-metallic inclusions by slag-metal reactions for high strength alloying steels, Steel Res. Int., 81(2010), No. 9, p. 759.
S.F. Yang, J.S. Li, Z.F. Wang, J. Li, and L. Lin, Modification of MgO·A12O3 spinel inclusions in Al-killed steel by Ca-treatment, Int. J. Miner. Metall. Mater., 18(2011), No. 1, p. 18.
Z.Y. Deng and M.Y. Zhu, Evolution mechanism of non-metallic inclusions in Al-killed alloyed steel during secondary refining process, ISIJ Int., 53(2013), No. 3, p. 450.
M. Jiang, B. Chen, W. Yang, and X.H. Wang, A study on thermodynamics of spinel inclusions formation in an alloy structural steel, Spec. Steel, 29(2008), No. 1, p. 16.
M. Jiang, X.H. Wang, B. Chen, and W.J. Wang, Formation of MgO·Al2O3 inclusions in high strength alloyed structural steel refined by CaO-SiO2-Al2O3-MgO slag, ISIJ Int., 48(2008), No. 7, p. 885.
H. Todoroki and K. Mizuno, Effect of silica in slag on inclusion compositions in 304 stainless steel deoxidized with aluminum, ISIJ Int., 44(2004), No. 8, p.1350.
J.H. Park and H. Todoroki, Control of MgO·Al2O3 spinel inclusions in stainless steels, ISIJ Int., 50(2010), No. 10, p. 1333.
K. Fujii, T. Nagasaka, and M. Hino, Activities of the constituents in spinel solid solution and free energies of formation of MgO, MgO·Al2O3, ISIJ Int., 40(2000), No. 11, p. 1059.
H. Lei, M.Y. Zhu, and J.C. He, Mathematical modeling of slag entrapment in continuous casting mould, Acta Metall. Sin., 36(2000), No. 10, p. 1113.
G. Okuyama, K. Yamaguchi, S. Takeuchi, and K. Sorimachi, Effect of slag composition on the kinetics of formation of Al2O3-MgO inclusions in aluminum killed ferritic stainless steel, ISIJ Int., 40(2000), No. 2, p. 121.
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Sun, Yh., Zeng, Yn., Xu, R. et al. Formation mechanism and control of MgO·Al2O3 inclusions in non-oriented silicon steel. Int J Miner Metall Mater 21, 1068–1076 (2014). https://doi.org/10.1007/s12613-014-1011-9
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DOI: https://doi.org/10.1007/s12613-014-1011-9