Numerical simulation on the multiphase flow and reoxidation of the molten steel in a two-strand tundish during ladle change

Abstract

A 3D mathematical model was proposed to investigate the molten steel–slag–air multiphase flow in a two-strand slab continuous casting (CC) tundish during ladle change. The study focused on the exposure of the molten steel and the subsequent reoxidation occurrence. The exposure of the molten steel was calculated using the coupled realizable k–ε model and volume of fluid (VOF) model. The diffusion of dissolved oxygen was determined by solving the user-defined scalar (UDS) equation. Moreover, the user-defined function (UDF) was used to describe the source term in the UDS equation and determine the oxidation rate and oxidation position. The effect of the refilling speed on the molten steel exposure and dissolved oxygen content was also discussed. Increasing the refilling speed during ladle change reduced the refilling time and the exposure duration of the molten steel. However, the elevated refilling speed enlarged the slag eyes and increased the average dissolved oxygen content within the tundish, thereby exacerbating the reoxidation phenomenon. In addition, the time required for the molten steel with a high dissolved oxygen content to exit the tundish varied with the refilling speed. When the inlet speed was 3.0 m·s⁻¹ during ladle change, the molten steel with a high dissolved oxygen content exited the outlet in a short period, reaching a maximum dissolved oxygen content of 0.000525wt%. Conversely, when the inlet speed was 1.8 m·s⁻¹, the maximum dissolved oxygen content was 0.000382wt%. The refilling speed during the ladle change process must be appropriately decreased to minimize reoxidation effects and enhance the steel product quality.

References

[1] Y. Zhong, M.M. Zhu, B. Huang, and A.P. Zhang, Numerical simulation study on design optimization of inner cavity dimensions of large-capacity tundish, [in] 10th International Symposium on High-temperature Metallurgical Processing, San Antonio, 2019, p. 51.

[2] M. Warzecha, Numerical and physical modelling of steel flow in a one-strand continuous casting tundish, Metalurgija, 50(2011), No. 3, art. No. 147.

[3] B.L. Zhang, F.H. Liu, R. Zhu, and J.F. Zhu, Effects of multiple-hole baffle arrangements on flow fields in a five-strand asymmetric tundish, Materials, 13(2020), No. 22, art. No. 5129.

[4] AiXG, HanD, LiSL, ZengHB, LiHY. Optimization of flow uniformity control device for six-stream continuous casting tundish. J. Iron Steel Res. Int., 2020, 27(9): 1035

[5] ZhangH, WangJH, FangQ, NiWH. Research progress on numerical simulation of transient tundish casting. J. Univ. Sci. Technol. Liaoning, 2021, 44(6): 401

[6] SahaiY. Tundish technology for casting clean steel: a review. Metall. Mater. Trans. B, 2016, 47(4): 2095

[7] ZhangLF. Inclusion and bubble in steel: a review. J. Iron Steel Res. Int., 2006, 13(3): 1

[8] WangYF, ZhangLF. Transient fluid flow phenomena during continuous casting: Part I—cast start. ISIJ Int., 2010, 50(12): 1777

[9] ChattopadhyayK, LiuFG, IsacM, GuthrieRIL. Effect of vertical alignment of ladle shroud on transient steel quality output from multistrand tundish. Ironmaking Steelmaking, 2013, 38(2): 112

[10] TanakaH, NishiharaR, KitagawaI, TsujinoR. Quantitative analysis of contamination of molten steel in tundish. ISIJ Int., 1993, 33(12): 1238

[11] ChenHL, LiuZT, LiFC, LyuBY, ChenW, ZhangLF. Numerical simulation on multiphase flow and slag entrainment during casting start of a slab continuous casting tundish. Metall. Mater. Trans. B, 2023, 54(4): 2048

[12] ZhangLF, ThomasBG. State of the art in the control of inclusions during steel ingot casting. Metall. Mater. Trans. B, 2006, 37(5): 733

[13] GuC, LiuWQ, LianJH, BaoYP. In-depth analysis of the fatigue mechanism induced by inclusions for high-strength bearing steels. Int. J. Miner. Metall. Mater., 2021, 28(5): 826

[14] WangZL, BaoYP. Development and prospects of molten steel deoxidation in steelmaking process. Int. J. Miner. Metall. Mater., 2024, 31(1): 18

[15] XiaoW, BaoYP, GuC, et al. . Ultrahigh cycle fatigue fracture mechanism of high-quality bearing steel obtained through different deoxidation methods. Int. J. Miner. Metall. Mater., 2021, 28(5): 804

[16] YangD, DengXX, WangXH, QianL. Effect of reoxidation on cleanliness of molten steel in tundish for low carbon aluminum killed steel. Iron Steel, 2013, 48(1): 37

[17] FanC, LiuZZ, CaiKK, et al. . Research on cleanliness of steel grade 45 produced by BOF–LF–CC process. Iron Steel, 2003, 38(3): 18

[18] WeiJ, ZhaoGY, CaiKK, ZhouYC, LvJQ, GaoYP. Investigation on non-metallic inclusions in low carbon Al-killed steel produced by CSP at Handan steel. Iron Steel, 2005, 40(6): 30

[19] SasaiK, MizukamiY. Oxidation rate of molten steel by argon gas blowing in tundish oxidizing atmosphere. ISIJ Int., 2011, 51(7): 1119

[20] NiPY, TanakaT, SuzukiM, NakamotoM, JønssonPG. A kinetic model on oxygen transfer at a steel/slag interface under effect of interfacial tension. ISIJ Int., 2018, 58(11): 1979

[21] SunYH, CaiKK, ZhaoCL. Effect of transient casting operation on cleanliness of continuously cast strands. Iron Steel, 2008, 43(1): 22

[22] Garcia-HernandezS, MoralesRD, de Jesus BarretoJ, Calderon-RamosI, GutierrezE. Modeling study of slag emulsification during ladle change-over using a dissipative ladle shroud. Steel Res. Int., 2016, 87(9): 1154

[23] R. Xu, H.T. Ling, H.J. Wang, L.Z. Chang, and S.T. Qiu, Investigation on the control of multiphase flow behavior in a continuous casting tundish during ladle change, Metall. Res. Technol., 117(2020), No. 6, art. No. 619.

[24] LingHT, XuR, WangHJ, ChangLZ, QiuST. Multiphase flow behavior in a single-strand continuous casting tundish during ladle change. ISIJ Int., 2020, 60(3): 499

[25] ZhangH, FangQ, LuoRH, LiuC, WangY, NiHW. Effect of ladle changeover condition on transient three-phase flow in a five-strand bloom casting tundish. Metall. Mater. Trans. B, 2019, 50(3): 1461

[26] JonesWP, LaunderBE. The prediction of laminarization with a two-equation model of turbulence. Int. J. Heat Mass Transfer, 1972, 15(2): 301

[27] HirtCW, NicholsBD. Volume of fluid (VOF) method for the dynamics of free boundaries. J. Comput. Phys., 1981, 39(1): 201

[28] N. Scapin, P. Costa, and L. Brandt, A volume-of-fluid method for interface-resolved simulations of phase-changing two-fluid flows, J. Comput. Phys., 407(2020), art. No. 109251.

[29] ZhangJ. Physical Chemistry of Metallurgy, 2004BeijingMetallurgical Industry Press317

[30] SasaiK, MizukamiY. Reoxidation behavior of molten steel in tundish. ISIJ Int., 2000, 40(1): 40

[31] KrishnapisharodyK, IronsGA. A unified approach to the fluid dynamics of gas-liquid plumes in ladle metallurgy. ISIJ Int., 2010, 50(10): 1413

[32] WangJJ, ZhangLF, ChengG, RenQ, RenY. Dynamic mass variation and multiphase interaction among steel, slag, lining refractory and nonmetallic inclusions: Laboratory experiments and mathematical prediction. Int. J. Miner. Metall. Mater., 2021, 28(8): 1298

[33] Y. Zhang, Y. Ren, and L.F. Zhang, Kinetic study on compositional variations of inclusions, steel and slag during refining process, Metall. Res. Technol., 115(2018), No. 4, art. No. 415.

[34] ZhaoYY, ChenW, ChengSS, ZhangLF. Mathematical simulation of hot metal desulfurization during KR process coupled with an unreacted core model. Int. J. Miner. Metall. Mater., 2022, 29(4): 758

[35] ZhangLF. Transient fluid flow phenomena in continuous casting tundishes. Iron Steel Technol., 2010, 7(7): 55

[36] RenQ, ZhangYX, RenY, ZhangLF, WangJJ, WangYD. Prediction of spatial distribution of the composition of inclusions on the entire cross section of a linepipe steel continuous casting slab. J. Mater. Sci. Technol., 2021, 61: 147