Abstract
In this article, the effect of CaS formation on the evolution of Al2O3-CaO inclusions in low-carbon Al-killed and Ca-treated steel during the solidification process is investigated through high-temperature confocal scanning laser microscopy (CSLM). The inclusions started as mostly liquid-globular inclusions that did not agglomerate with each other on the melt surface but during solidification were seen to change shape into an irregular morphology. The shape change was found to be due to the reaction between the Al2O3-CaO inclusions with the dissolved S and Al in the melt, resulting in the formation of dense CaS shells around the inclusions. The melt composition during solidification, estimated from the observed solid δ-front advance rate, was compared to the thermodynamic limit for CaS precipitation. The observed growth rate of the CaS shell was found to initially increase with decreasing temperature because of the higher, solid δ-front advance rates at lower temperatures, which results in higher rates of S and Al partitioning. Once CaS had precipitated, the inclusions were found to form agglomerates on the melt surface because of fluid flow, initially, and later, the capillary depression.
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C. Gatellier, H. Gaye, J. Lehmann, J.N. Pontoire, and P.V. Riboud: Steel Res., 1993, vol. 64 (1), pp. 87–92.
L.E. Iorio and W.M. Garrison: Iron and Steel Society/AIME, 41st Mechanical Working and Steel Processing Conf. Proc., Iron and Steel Society/AIME, Warrendale, PA, 1999, vol. 37, pp. 843–50.
C. Orrling, S. Sridhar, and A.W. Cramb: Iron Steel Inst. Jpn. Int., 2000, vol. 40, pp. 877–85.
S. Okhita, H. Homma, S. Tsushima, and N. Mori: Aus. Welding J., 1984, vol. 29, pp. 29–36.
G.J.W. Kor: Proc. 1st Int. Calcium Treatment Symp., University of Strathclyde, Glasgow, Scotland, June 30, 1988, The Institute of Metals, London, 1988, pp. 39–44.
J.W. Farrell and D.C. Hilty: Proc. Electric Furnace Conf., The Metallurgical Society/AIME, Warrendale, PA, 1971, vol. 29, pp. 31–46.
S. Dawson, N.D.G. Mountford, I.D. Sommerville and A. McLean: Proc. 1st Int. Calcium Treatment Symp., University of Strathclyde, Glasgow, Scotland, 1988, pp. 109–116.
J.M.A. Geldenhuis and P.C. Pistorius: Ironmaking and Steelmaking (UK), 2000, vol. 27, pp. 442–49.
D. Coulombert, L. Sancho, and B. Schaffer: Proc. 1st Int. Calcium Treatment Symp., University of Strathclyde, Glasgow, Scotland, June 30, 1988, The Institute of Metals, London, 1988, pp. 83–87.
R.H. Rein and J. Chipman: Trans. AIME, 1965, vol. 233, pp. 415–25.
R.A. Sharma and F.D. Richardson: J. Iron Steel Inst., 1961, vol. 198, pp. 409–18.
T. Fujisawa, C. Yamauchi, and H. Sakao: Proc. 6th Int. Iron and Steel Congress, ISIJ, Tokyo, 1990, vol. 1, pp. 201–08.
G. Eriksson and A. Pelton: Metall. Trans. B, 1993, vol. 24B, pp. 807–16.
J.F. Elliott, M. Gleiser, and V. Ramakrishna: Thermochemistry for Steelmaking, Addison-Wesley Publishing Company, Reading, MA, 1963, p. 462.
R. Inoue and H. Suito: Steel Res., 1994, vol. 65, pp. 403–09.
E.T. Turkdogan: Proc. 1st Int. Calcium Treatment Symp., University of Strathclyde, Glasgow, Scotland, June 30, 1988, The Institute of Metals, London, 1988, pp. 3–13.
K. Larsen and R.J. Fruehan: Trans. ISS. 1990, vol. 17, pp. 45–52.
G. Ye, P. Jönsson, and T. Lund: Iron Steel Inst. Jpn. Int., 1996, vol. 36, pp. 105–08.
E. Martinez: Iron and Steelmaker (USA), 1995, vol. 22, pp. 19–23.
C. Cicutti, M. Valdez, T. Pérez, R. Ares, R. Panelli, and J. Petroni: 84th Steelmaking Conf. Proc., Baltimore, MD, Mar. 25, 2001, Iron and Steel Society, Warrendale, PA, 2001, pp. 871–82.
Y. Wang, M. Valdez, and S. Sridhar: Z. Metallkd., 2002, vol. 93 (1), pp. 1–9.
C. Orring, Y. Fang, N. Phinichka, S. Sridhar, and A.W. Cramb: JOM-e, 1999, vol. 51 (7).
H. Yin, H. Shibata, T. Emi, and M. Suzuki: Iron Steel Inst. Jpn. Int., 1997, vol. 37, pp. 946–55.
E.T. Turdogan: Fundamentals of Steelmaking, The University Press, Cambridge, United Kingdom, p. 298.
K. Nishikawa, K. Ito, and K. Sano: Tetsu-to-Hagané, 1970, vol. 56 (12), pp. 1467–76.
H. Yin, H. Shibata, T. Emi, and M. Suzuki: Iron Steel Inst. Jpn. Int., 1997, vol. 37, pp. 936–45.
D.R. Gaskell: Introduction to the Thermodynamics of Materials, 3rd ed., Taylor & Francis, Washington, DC, pp. 544–45.
E.T. Turkdogan: Physical Chemistry of High Temperature Technology, Academic Press, New York, NY, pp. 5–24.
J. Björkvall, S.C. Du, and S. Seetharaman: CALPHAD, 2000, vol. 24 (3), pp. 353–76.
C.H.P. Lupis: Chemical Thermodynamics of Materials, P.T.R. Prentice Hall, Englewood Cliffs, NJ, pp. 240–59.
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Wang, Y., Sridhar, S. & Valdez, M. Formation of CaS on Al2O3-CaO inclusions during solidification of steels. Metall Mater Trans B 33, 625–632 (2002). https://doi.org/10.1007/s11663-002-0042-1
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DOI: https://doi.org/10.1007/s11663-002-0042-1