Grain growth kinetics model of high-temperature ferrite and austenite in Ti microalloyed steel during continuous casting

Abstract

The microstructural characteristics of austenite in Ti microalloyed steel during continuous casting significantly influence the thermoplasticity, thereby affecting the quality of the slab. In this work, a prediction model for two-stage austenite growth under varying cooling rates was established by incorporating the effect of second-phase pinning and high-temperature ferrite–austenite phase transformation and growth theory. The results indicate that with 0.02wt% Ti, the high-temperature ferrite growth exhibits typical parabolic growth characteristics. When the Ti content increases to 0.04wt%, the high-temperature ferrite grain boundary migration rate significantly slows during the initial solidification stage. The predicted austenite grain sizes for 0.02wt% Ti microalloyed steel at the center, quarter, and surface of the slab are 5592, 3529, and 1524 µm, respectively. For 0.04wt% Ti microalloyed steel, the austenite grain sizes are 4074, 2942, and 1179 µm at the same positions. The average error is within 5%. As the Ti content increases from 0.02wt% to 0.04wt%, the austenite grain refinement at the center is most significant, with an average grain size reduction of 27.14%.

Keywords

Ti microalloyed steel / slab continuous casting / phase transfer / Ti carbonitrides / austenite growth kinetics

References

[1] YangJP, LiuQ, GuoWD, ZhangJG. Quantitative evaluation of multi-process collaborative operation in steelmaking–continuous casting sections. Int. J. Miner. Metall. Mater., 2021, 28(8): 1353

[2] LiQH, LanP, WangHJ, AiHZ, ChenDL, WangHD. Formation and control of the surface defect in hypo-peritectic steel during continuous casting: A review. Int. J. Miner. Metall. Mater., 2023, 30(12): 2281

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

[4] ZhuMY, WangWX. Numerical simulation of the deformation risk in thin slab continuous casting process with liquid core reduction. Int. J. Miner. Metall. Mater., 2025, 32(5): 1114

[5] AnJZ, CaiZZ, ZhuMY. Effect of titanium content on the refinement of coarse columnar austenite grains during the solidification of peritectic steel. Int. J. Miner. Metall. Mater., 2022, 29(12): 2172

[6] Y.D. Wang, Q. Ren, L.F. Zhang, et al., Formation and control of transverse corner cracks in the continuous casting slab of a microalloyed steel, Steel Res. Int., 92(2021), No. 6, art. No. 2000649.

[7] R.M. Pineda Huitron, P.E. Ramirez Lopez, E. Vuorinen, R. Jentner, and M.E. Kärkkäinen, Converging criteria to characterize crack susceptibility in a micro-alloyed steel during continuous casting, Mater. Sci. Eng. A, 772(2020), art. No. 138691.

[8] LabonneM, GrauxA, CazottesS, et al.. Precipitation kinetics in a Nb-stabilized ferritic stainless steel. Metall. Mater. Trans. A, 2017, 48(8): 3655

[9] ChamanfarA, ChentoufSM, JahaziM, Lapierre-BoireLP. Austenite grain growth and hot deformation behavior in a medium carbon low alloy steel. J. Mater. Res. Technol., 2020, 9(6): 12102

[10] XuY, LiuJS, ZhaoY, JiaoYX. Austenite grain growth kinetics and mechanism of grain growth in 12Cr ultra-supercritical rotor steel. Philos. Mag., 2021, 101(1): 77

[11] F. Zhao, H. Hu, X.H. Liu, Z.H. Zhang, and J.X. Xie, Effect of billet microstructure and deformation on austenite grain growth in forging heating of a medium-carbon microalloyed steel, J. Alloy. Compd., 869(2021), art. No. 159326.

[12] LeeSJ, LeeYK. Prediction of austenite grain growth during austenitization of low alloy steels. Mater. Des., 2008, 29(9): 1840

[13] HuH, RathBB. On the time exponent in isothermal grain growth. Metall. Trans., 1970, 1(11): 3181

[14] AndersenI, GrongØ. Analytical modelling of grain growth in metals and alloys in the presence of growing and dissolving precipitates—I. Normal grain growth. Acta Metall. Mater., 1995, 43(7): 2673

[15] PattersonBR, LiuY. Relationship between grain boundary curvature and grain size. Metall. Trans. A, 1992, 23(9): 2481

[16] EskandariH, ReihanianM, ZareeSRA. Constitutive modeling, processing map optimization, and recrystallization kinetics of high-grade X80 pipeline steel. J. Mater. Res. Technol., 2024, 33: 2315

[17] NesE, RyumN, HunderiO. On the Zener drag. Acta Metall., 1985, 33(1): 11

[18] YoshidaN, UmezawaO, NagaiK. Analysis on refinement of columnar γ grain by phosphorus in continuously cast 0.1 mass% carbon steel. ISIJ Int., 2004, 44(3): 547

[19] EnomotoM, HayashiK. Estimation of austenite grain boundary mobility in low-carbon steel by grain growth. J. Mater. Sci., 2023, 58(10): 4603

[20] M. Kern, M. Bernhard, C. Bernhard, and Y.B. Kang, Grain boundary mobility of γ-Fe in high-purity iron during isothermal annealing, Scripta Mater., 230(2023), art. No. 115431.

[21] WangSZ, GaoZJ, WuGL, MaoXP. Titanium microalloying of steel: A review of its effects on processing, microstructure and mechanical properties. Int. J. Miner. Metall. Mater., 2022, 29(4): 645

[22] AnJZ, CaiZZ, ChengB, ZhuMY. Nb–Ti composite precipitation behaviour and its effect on the growth of austenite grains in peritectic steel. Ironmaking Steelmaking, 2022, 50(7): 1

[23] JiC, WuCH, ZhuMY. Thermo-mechanical behavior of the continuous casting bloom in the heavy reduction process. JOM, 2016, 68(12): 3107

[24] WangJC, LiuZT, ChenW, ChenHL, ZhangLF. Numerical simulation on the multiphase flow and reoxidation of the molten steel in a two-strand tundish during ladle change. Int. J. Miner. Metall. Mater., 2024, 31(7): 1540-1553

[25] JiC, ChenTC, ZhuMY. Carbonitride precipitation kinetics model during continuous casting of Ti microalloyed steel. Metall. Mater. Trans. A, 2024, 55(8): 3045

[26] ChenY, JiC, ZhuMY. Prediction model of the proeutectoid ferrite growth of a continuous casting slab. Metall. Mater. Trans. A, 2023, 54(4): 1101

[27] TurnbullD. Theory of grain boundary migration rates. JOM, 1951, 3(8): 661

[28] ZhouTH, O’malleyRJ, ZurobHS. Study of grain-growth kinetics in delta-ferrite and austenite with application to thin-slab cast direct-rolling microalloyed steels. Metall. Mater. Trans. A, 2010, 41(8): 2112

[29] HumphreysF J, HatherlyMRecrystallization and Related Annealing Phenomena, 20042nd ed.Oxford, Elsevier Ltd.: 335

[30] TangPZ, ZhangHH, LongMJ, ChenDF, WangK. A prediction model for continuous growth of austenite grains in steel casting blank: Considering complex temperature variation. Metall. Mater. Trans. B, 2024, 55(1): 195

[31] HarunA, HolmEA, ClodeMP, MiodownikM A. On computer simulation methods to model zener pinning. Acta Metall., 2006, 54(12): 3261

[32] T. Shimokawa, K. Fujii, and T. Niiyama, Atomic simulation study of the factors affecting nucleation in deformation-induced martensitic transformation in grains and at grain boundaries in pure iron, Acta Mater., 265(2024), art. No. 119629.

RIGHTS & PERMISSIONS

University of Science and Technology Beijing