Crystallization behaviors of the newly developed lime-alumina-based mold fluxes for high-aluminum transformation induced plasticity (TRIP) steels casting were experimentally studied, and compared with those of lime-silica-based mold fluxes. The effects of mold flux crystallization characteristics on heat transfer and lubrication performance in casting high-Al TRIP steels were also evaluated. The results show that the crystallization temperatures of lime-alumina-based mold fluxes are much lower than those of lime-silica-based mold fluxes. Increasing B2O3 addition suppresses the crystallization of lime-alumina-based mold fluxes, while Na2O exhibits an opposite effect. In continuous cooling of lime-alumina-based mold fluxes with high B2O3 contents and a CaO/Al2O3 ratio of 3.3, faceted cuspidine precipitates first, followed by needle-like CaO·B2O3 or 9CaO·3B2O3·CaF2. In lime-alumina-based mold flux with low B2O3 content (5.4 mass pct) and a CaO/Al2O3 ratio of 1.2, the formation of fine CaF2 takes place first, followed by blocky interconnected CaO·2Al2O3 as the dominant crystalline phase, and rod-like 2CaO·B2O3 precipitates at lower temperature during continuous cooling of the mold flux. In B2O3-free mold flux, blocky interconnected 3CaO·Al2O3 precipitates after CaF2 and 3CaO·2SiO2 formation, and takes up almost the whole crystalline fraction. The casting trials show that the mold heat transfer rate significantly decreases near the meniscus during the continuous casting using lime-alumina-mold fluxes with higher crystallinity, which brings a great reduction of surface depressions on cast slabs. However, excessive crystallinity of mold flux causes poor lubrication between mold and solidifying steel shell, which induces various defects such as drag marks on cast slab. Among the studied mold fluxes, lime-alumina-based mold fluxes with higher B2O3 contents and a CaO/Al2O3 ratio of 3.3 show comparatively improved performance.
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B. Sauerhammer, D. Senk, E. Schmidt, M. Safi, M. Spiegel, and S. Sridhar: Metall. Mater. Trans. B, 2005, vol. 36B, pp. 503 512.
M. Gomez, C.I. Garcia, and A.J. Deardo: ISIJ Int., 2010, vol. 50, pp. 139 146.
D.W. Suh, S.J. Park, C.S. Oh, and S.J. Kim: Scripta Mater., 2007, vol. 57, pp. 1097 1100.
M.D. Meyer, D. Vanderschueren, and B.C.De Cooman: ISIJ Int., 1999, vol. 39, pp. 813 822.
T.L. Baum, R.J. Fruehan, and S. Sridhar: Metall. Mater. Trans. B, 2007, vol. 38B, pp. 287 297.
P. J. Jacques, E. Girault, A. Mertens, B. Verlinden, J. Humbeeck, and F. Delannay: ISIJ Int., 2001, vol. 41, pp. 1068 1074.
J.J. Becker, M.A. Madden, T.T. Natarajan, T.J. Piccone, E.J. Serrano, S.R. Story, S.C. Ecklund-Baker, I.A. Nickerson, and W.K. Schlichting: AISTech 2005 Conf. Proc., vol. II, Association for Iron & Steel Technology, Charlotte, NC, 2005, pp. 99–106.
S. Street, K. James, N. Minor, A. Roelant, and J. Tremp: Iron Steel Technol., 2008, vol. 5, pp. 38 49.
K. Blazek, H.B. Yin, G. Skoczylas, M. McClymonds, and M. Frazee: Iron Steel Technol., 2011, vol. 8, pp. 232 240.
W.L. Wang, K. Blazek, and A. Cramb: Metall. Mater. Trans. B, 2008, vol. 39B, pp. 66 74.
J.W. Cho, K. Blazek, M. Frazee, H.B. Yin, J.H. Park, and S.W. Moon: ISIJ Int., 2013, vol. 53, pp. 62 70.
T. Wu, Q. Wang, S. He, J. Xu, X. Long, and Y. Lu: Steel Res. Int., 2012, vol. 83, pp. 1194 1202.
K.C. Mills, A.B. Fox, Z. Li, and R.P. Thackray: Ironmaking Steelmaking, 2005, vol. 32, pp. 26 34.
Y. Kashiwaya, C.E. Cicutti, and A.W. Cramb: ISIJ Int., 1998, vol. 38, pp. 357 365.
H. Liu, G. Wen, and P. Tang: ISIJ Int., 2009, vol. 49, pp. 843 850.
L. Zhou, W. Wang, F. Ma, J. Li, J. Wei, H. Matsuura, and F. Tsukihashi: Metall. Mater. Trans. B, 2012, vol. 43B, pp. 354 362.
J. Li, W. Wang, J. Wei, D. Huang, and H. Matsuura: ISIJ Int., 2012, vol. 52, pp. 2220 2225.
B. Lu, W. Wang, J. Li, H. Zhao, and D. Huang: Metall. Mater. Trans. B, 2013, vol. 44B, pp. 365 377.
L. Zhou, W. Wang, D. Huang, J. Wei, and J. Li: Metall. Mater. Trans. B, 2012, vol. 43B, pp. 925 936.
L. Zhou, W. Wang, R. Liu, and B.G. Thomas: Metall. Mater. Trans. B, 2013, vol. 44B, 1264 1279.
Z. Hao, W. Chen, and C. Lippold: Metall. Mater. Trans. B, 2010, vol. 41B, pp. 805 812.
T. Watanabe, H. Hashimoto, M. Hayashi, and K. Nagata: ISIJ Int., 2008, vol. 48, pp. 925 933.
K. Tsutsumti. T. Nagasaka, and M. Hino: ISIJ Int., 1999, vol. 39, pp. 1150-1159.
Z.T. Zhang, G.H. Wen, J.L. Liao, and S. Sridhar: Steel Res. Int., 2010, vol. 81, pp. 516 528.
H.G. Ryu, Z.T. Zhang, J.W. Cho, G.H. Wen, and S. Sridhar: ISIJ Int., 2010, vol. 50, pp. 1142 1150.
M. Hanao: ISIJ Int., 2013, vol. 53, pp. 648 654.
M.D. Seo, C.B. Shi, J.W. Cho, and S.H. Kim: Unpublished research.
H. Nakada and K. Nagata: ISIJ Int., 2006, vol. 46, pp. 441 449.
The authors would like to express sincere thanks to Mr. Seung-ho Shin and Mr. Min-su Kim of Graduate Institute of Ferrous Technology, POSTECH for their help in preparing mold flux samples. This work was financially supported by the Global Excellent Technology Innovation (Grant No. 10045029) funded by the Ministry of Trade, Industry & Energy (MOTIE) of Korea.
Manuscript submitted December 9, 2013.
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Shi, C., Seo, M., Cho, J. et al. Crystallization Characteristics of CaO-Al2O3-Based Mold Flux and Their Effects on In-Mold Performance during High-Aluminum TRIP Steels Continuous Casting. Metall Mater Trans B 45, 1081–1097 (2014). https://doi.org/10.1007/s11663-014-0034-y
- Differential Scanning Calorimetry
- Differential Scanning Calorimetry Curve
- Mold Flux
- Differential Scanning Calorimetry Measurement