Flow Dynamics and Inclusion Transport in Continuous Casting of Steel

Brian G. Thomas, S.P. Vanka, Lifeng Zhang, Quan Yuan and Bin Zhao.

National Science Foundation GOALI # DMI-0115486 and
Continuous Casting Consortium


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Project Overview
NSF and Industry Support
Significant Results
Impact
NSF Publications

Project Overview

Computational models of transient, multiphase fluid flow are being developed, validated, and applied to improve understanding of transient flow, inclusion transport and defect formation in the mold region during the continuous casting of steel slabs. Process parameters, such as nozzle geometry and gas injection rate, which are easy to change and yet profoundly influence both flow and product quality, are being optimized. Models to compute the transport and entrapment of inclusion particles are being tested through water model experiments, steel plant trials, and metallographic measurements at several steel companies who are cosponsoring this research.

National Science Foundation Support:

DMI 0115486; Sept. 2001 - Sept. 2004

Industry Support and Partnerships:

Continuous Casting Consortium

Provided: Financial Support (CCC membership); In-kind Support; Facilities (water models and plant measurements); and Research direction, are provided by:

LTV Steel (Cleveland,OH)
AK Steel Company (Middletown, OH)
IAllegheny Ludlum (Brackenridge, PA)
Columbus Stainless Steel (Middleburg, SA),
Stolberg, (Niagara Falls, NY),
Hatch Associates, (Buffalo, NY),
Accumold, (Huron Park, Ontario)

Significant Results

Several different computational models of turbulent fluid flow and heat transfer have been developed to simulate flow phenomena in the nozzle and mold regions of the continuous casting of steel slabs. The models are being calibrated, validated, and tested through water model experiments, steel plant trials, and metallographic measurements at several steel companies, who are cosponsoring this research. Large Eddy Simulation model predictions have identified important time-dependent flow features, which match water model measurements (conducted using digital Particle Image Velocimetry). Furthermore, particle trajectories calculated in the transient flow field reasonably match water model measurements of the distribution and fraction of the injected particles removed by flotation. Time-average flow fields with both LES and k-e models roughly agree with both water model and steel caster measurements for single-phase flow. Recent k-e model simulations with multiple bubble size distributions have shown differences between multiphase flow in a 0.4-scale water model and flow in the steel caster. Separate predictions have matched measurements in both systems. In addition to the inlet velocity and direction, the turbulence and swirl at the inlet ports has been shown to be very important to both the fluid flow and inclusion motion.

Impact

This work aims to improve understanding of transient flow, inclusion transport and defect formation in the mold region during the continuous casting of steel slabs, through the development, validation, and application of fundamental computational models of transient fluid flow. Plant observations have found that many serious quality problems, including inclusion entrapment, are directly associated with the flow pattern in the mold. The results from the computational simulations of this work are increasing fundamental understanding of transient fluid flow, gas, and inclusion particle transport in the mold region. This will lead to optimized nozzle geometry and gas flow rates to improve mold flow patterns and minimize inclusion defects. Lowering defects from internal inclusions can improve steel minimum strength, fatigue life, surface appearance, yield and energy efficiency (from reduced rejects) and lower production cost. If successful, this will help the domestic steel industry to maintain competitiveness in the global economy. Furthermore, the computational tools developed and validated in this work can be applied to study and optimize flow to improve other processes.

NSF Publications

Thomas, B.G., and S.P. Vanka; “Flow Dynamics and Inclusion Transport in Continuous Casting of Steel”, Proceedings of the 2002 NSF Design, Service, Manufacturing and Industrial Innovation Research Conf., San Juan, Puerto Rico, Jan. 7-10 2002, NSF, Washington, D.C., 22p. Download 1040 KB pdf


Thomas, B.G., Q, Yuan, L. Zhang, and S.P. Vanka, "Flow Dynamics and Inclusion Transport in the Continuous Casting of Steel," 2003 NSF Design, Service, and Manufacturing Grantees and Research Conf. Proceedings, R.G. Reddy, ed., (Burmingham, AL, Jan. 6-9, 2003), University of Alabama, Tuscaloosa, AL 35498, USA, pp. 2328-2362. Download 675 KB pdf


Thomas B.G., Q. Yuan, L. Zhang, B. Zhao, and S.P. Vanka, "Flow Dynamics and Inclusion Transport in Continuous Casting of Steel," 2004 NSF Design, Service, and Manufacture and Industrial Innovation Grantees and Research Conf. Proceedings, (Dallas, TX, Jan. 5-8, 2004), Southern Methodist University, Dallas, TX, USA. Download 891 KB pdf

Thomas, B.G., "Modeling of the Continuous Casting of Steel: Past, Present, and Future, Dr. J. Keith Brimacombe Lecture," Metal. & Material Trans., Vol. 33B (Dec.),2002, 795-812.

Zhang, L. and B.G. Thomas, "State of the Art in Evaluation and Control of Steel Cleanliness," ISIJ International, Vol. 43 (3),2003, 271-291.

Meng, Y. and B.G. Thomas, "Heat Transfer and Solidification Model of Continuous Slab Casting: CON1D," Metal. & Material Trans., Vol. 34B (5),2003, 685-705.

Meng, Y. and B.G. Thomas, "Interfacial Friction-Related Phenomena in Continuous Casting with Mold Slags," Metall. & Materials Trans. B, Vol. 34B (5),2003, 707-725.

Yuan, Q., B.G. Thomas and S.P. Vanka, "Study of Transient Flow and Particle Transport during Continuous Casting of Steel Slabs, Part 1.  Fluid Flow," Metal. & Material Trans. B., Vol. 35B (4),2004, 685-702.

Yuan, Q., S. Sivaramakrishnan, S.P. Vanka and B.G. Thomas, "Computational and Experimental Study of Turbulent Flow in a 0.4-Scale Water Model of a Continuous Steel Caster," Metall. & Mater. Trans., Vol. 35B (5),2004, 967-982.

Yuan, Q., B.G. Thomas and S.P. Vanka, "Study of Transient Flow and Particle Transport during Continuous Casting of Steel Slabs, Part 2.  Particle Transport.," Metal. & Material Trans. B., Vol. 35B (4),2004, 703-714.

Yuan, Q., B. Zhao, S.P. Vanka, and B.G. Thomas, "Study of Computational Issues in Simulation of Transient Flow in Continuous Casting," Steel Research International, Vol. 76 (1, Special Issue: Simulation of Fluid Flow in Metallurgy),2005, 33-43.

Zhao, B., S.P. Vanka and B.G. Thomas, "Numerical Study of Flow and Heat Transfer in a Molten Flux Layer," Int. J. Heat and Fluid Flow, Vol. 26,2005, 105-118.

Zhao, B., B.G. Thomas, S.P. Vanka and R.J. O’Malley, "Transient Fluid Flow and Superheat Transport in Continuous Casting of Steel Slabs," Metallurgical and Materials Transactions B (in press),2005.

Zhao, B., B.G. Thomas, S.P. Vanka and R.J. O’Malley, "Transient Flow and Temperature Transport in Continuous Casting of Steel Slabs," ASME J. Heat Transfer, Vol. 127,2005, 807.

Zhang, L., J. Cui, J. Zhi, L. Zhu, X. Jiang, J. Zheng, J. Mou, K. Cai and B.G. Thomas, "Investigation of Steel Cleanliness at Baosteel," Ironmaking & Steelmaking (submitted July 8),2005.

Zhang, L., Jun Aoki and B.G. Thomas, "Inclusion Removal by Bubble Flotation in a Continuous Casting Mold," Metallurgical and Materials Transactions B (submitted August 4),2005.

Zhang, L. and B.G. Thomas, "State of the Art in the Control of Inclusions during Steel Ingot Casting," Metallurgical and Materials Transactions B (submitted August),2005.

Zhang, L., S. Yang, X. Wang, K. Cai, J. Li, X. Wan and B.G. Thomas, "Investigation of Fluid Flow and Steel Cleanliness in the Continuous Casting Strand," Metallurgical and Materials Transactions B (submitted June 13),2005.

Thomas, B.G., M. Jenkins and R.B. Mahapatra, "Investigation of Strand Surface Defects Using Mold Instrumentation and Modeling," Ironmaking & Steelmaking, Vol. 31,2004, 485-494.  (no acknowledgement to NSF)

Zhang, L., W. Pluschkell, and B.G. Thomas, "Nucleation and Growth of Alumina Inclusions During Steel Deoxidation," in Steelmaking Conf. Proc., Vol. 85, ISS, Warrendale, PA, (Nashville, March 10-13, 2002), 2002, 463-476.

Zhang, L., B.G. Thomas, X. Wang, and K. Cai, "Evaluation And Control Of Steel Cleanliness - A Review," in Steelmaking Conf. Proc., Vol. 85, ISS, Warrendale, PA, (Nashville, TN, March 10-13, 2002), 2002, 431-452.

Zhang, L. and B.G. Thomas, "Alumina Inclusion Behavior During Steel Deoxidation," 7th European Electric Steelmaking Conference, (May 26-29, 2002, Venice, Italy), Associazione Italiana di Metallurgia, Milano, Italy, Vol. 2, 2002, 2.77-2.86.

Thomas, B.G., "Annual Report to Continuous Casting Consortium," University of Illinois at Urbana-Champaign, Oct. 15, 2002.

Meng, Y. and B.G. Thomas, "Interfacial Friction-Related Phenomena in Continuous Casting with Mold Slags," in ISSTech 2003 Steelmaking Conf. Proc., Vol. 86, ISS, Warrendale, PA, (Indianapolis, IN, Apr. 27-30, 2003), 2003, 589-606.

Yuan, Q., B.G. Thomas and S.P. Vanka, "Turbulent Flow and Particle Motion in Continuous Slab-Casting Molds," in ISSTech 2003 Process Technology Proceedings, Vol. 86, ISS, Warrendale, PA, (Indianapolis, IN, Apr 27-30, 2003), 2003, 913-927.

Zhang, L., B.G. Thomas, Kaike Cai, Jian Cui and L. Zhu, "Inclusion Investigation during Clean Steel Production at Baosteel," in ISSTech 2003 Steelmaking Conf. Proc., Vol. 86, ISS, Warrendale, PA, (Indianapolis, IN, Apr. 27-30, 2003), 2003, 141-156.

Yuan, Q., S.P. Vanka and B.G. Thomas, "Large Eddy Simulations of Transient Flow during Continuous Slab Casting of Steel," in 3rd International Symposium on Turbulenece and Shear Flow Phenomena, Vol. 2, (Sendai, Japan, June 25-27, 2003), 2003, 681-686.

Zhang, L. and B.G. Thomas, "Inclusions in Continuous Casting of Steel", XXIV National Steelmaking Symposium,," XXIV National Steelmaking Symposium, (Morelia, Mich, Mexico, Nov. 26-28, 2003), 2003, 138-183.

Zhang, L. and B.G. Thomas, "Fluid Flow and Inclusion Motion in the Continuous Casting Strand," in XXIV National Steelmaking Symposium, (Morelia, Mich, Mexico, Nov. 26-28, 2003), 2003, 184-198.

Zhang, L. and B.G. Thomas, "Inclusion Nucleation, Growth, and Mixing during Steel Deoxidation," Continuous Casting Consortium Report, No. CCC200206, University of Illinois at Urbana-Champaign, 2003, 1-19.

Thomas, B.G., "Chapter 5. Modeling of Continuous Casting," in Making, Shaping and Treating of Steel: Continuous Casting, Vol. 5, A. Cramb, ed. AISE Steel Foundation, Pittsburgh, PA, 2003, 5.1-5.24.

Thomas, B.G., "Chapter 14. Fluid Flow in the Mold," in Making, Shaping and Treating of Steel: Continuous Casting, Vol. 5, A. Cramb, ed. AISE Steel Foundation, Pittsburgh, PA, 2003, 14.1-14.41.

Thomas, B.G., "Recent Advances in Computational Modeling of Continuous Casting Steel," Scanmet II Conference, (Lulea, Sweden, June 6-9, 2004), MEFOS, Vol. 1, 2004, 243-252.

Yuan, Q., B. Zhao, S.P. Vanka and B.G. Thomas, "Study of Computational Issues in Simulation of Transient Flow in Continuous Casting," Materials Science & Technology 2004, (New Orleans, LA, Sept. 26-29), TMS, Warrendale, PA, Vol. II, 2004, 333-343.

Yuan, Q., "Transient Study of Turbulent Flow and Particle Transport During Continuous Casting of Steel Slabs," PhD Thesis, University of Illinois at Urbana-Champaign, IL, 2004.

Zhang, L., S. Yang, X. Wang, K. Cai, J. Li, X. Wan and B.G. Thomas, "Physical, Numerical and Industrial Investigation of Fluid Flow and Steel Cleanliness in the Continuous Casting Mold at Panzhihua Steel," in AISTech2004, ISS, Warrendale, PA, (Nashville, TN), 2004, 879-894.

Zhang, L., J. Aoki and B.G. Thomas, "Inclusion Removal by Bubble Flotation in Continuous Casting," in Materials Science & Technology 2004 (MS&T'04), Vol. 2, TMS & AIST, Warrendale, PA, (Sep.26-29, 2004, New Orleans, Louisiana, USA), 2004, 161-178.

Thomas, B.G., "Computational Modeling of Flow, Heat Transfer, and Deformation in the Continuous Casting of Steel," First Baosteel Annual Academic Conference, (Shanghai, China, May 27-28, 2004), Vol. 1, 2004, 13-19.

Yuan, Q. and B.G. Thomas, "Transport and Entrapment of Particles in Continuous Casting of Steel," 3rd Internat. Congress on Science & Technology of Steelmaking, (Charlotte, NC, May 9-11, 2005), Association for Iron & Steel Technology, Warrendale, PA, 2005, 745-762.

Zhao, B., "Numerical Study of Heat Transfer in Continuous Casting of Steel," MS Thesis, University of Illinois at Urbana-Champaign, 2003.

Zhang, L. and B.G. Thomas, "Application of Computational Fluid Dynamics to Steel Refining and Casting Processes," Fourth Internat. Conf. on CFD in Oil, Gas, Metall. & Process Industries, (Trondheim, Norway, 6-8 June 2005), SINTEF / NTNU Vol. 30, 2005.

Thomas, B.G., "Modeling of Continuous-Casting Defects Related to Mold Fluid Flow," 3rd Internat. Congress on Science & Technology of Steelmaking, (Charlotte, NC, May 9-11, 2005), Association for Iron & Steel Technology, Warrendale, PA, 2005, 847-862.

Thomas, B.G., "Mathematical Modeling of Continuous Casting of Steel," Annual Report to Continuous Casting Consortium, University of Illinois at Urbana-Champaign, June 1, 2005.

Thomas, B.G., L. Zhang, Q. Yuan and S.P. Vanka, "Flow Dynamics and Inclusion Transport in Continuous Casting of Steel," 2005 NSF Design, Manufacture and Industrial Innovation Grantees Conf. Proceedings, (Scottsdale, AZ, Jan. 3-6, 2005, Jan. 3-6, 2005), Arizona State Univ., Tempe, AZ, Vol. MPM #DMI0115486, 2005, T/BGT/1-24.

Aoki, J., Lifeng Zhang and B.G. Thomas, "Modeling of Inclusion Removal in Ladle Refining," 3rd Internat. Congress on Science & Technology of Steelmaking, (Charlotte, NC, May 9-11, 2005), Association for Iron & Steel Technology, Warrendale, PA, 2005, 319-332.

Zhang, L., B. Rietow, B.G. Thomas, K. Eakin, and D.Q. Baird, "Investigation of Steel Cleanliness during Ingot Teeming, Final Report to Ingot Metallurgy Forum," Ingot Metallurgy Forum Fall Meeting, (Canton, OH, Nov. 2, 2005), IMF, 2005.

Thomas, B.G., "On-line Detection of Quality Problems in Continuous Casting of Steel" in Modeling, Control and Optimization in Ferrous and Nonferrous Industry, F. Kongoli, B.G. Thomas and K. Sawamiphakdi, eds., TMS, Warrendale, PA, 2003, 2003, 29-45.