Modelling of macrosegregation in steel ingots: benchmark validation and industrial application

Abstract:The flow, temperature, solidification, and solute concentration field in a continuous casting bloom mold were solved simultaneously by a multiphysics numerical model by considering the effect of in-mold electromagnetic stirring (M-EMS). The mold metallurgical differences between cases with and without EMS are discussed first, and then the solute transport model verified. Moreover, the effects of EMS current intensity on the metallurgical behavior in the bloom mold were also investigated. The simulated solute distributions were basically consistent with the test results. The simulations showed that M-EMS can apparently homogenize the initial solidified shell, liquid steel temperature, and solute element in the EMS effective zone. Meanwhile, the impingement effect of jet flow and molten steel superheat can be reduced, and the degree of negative segregation in the solidified shell at the mold corner alleviated from 0.74 to 0.78. However, the level fluctuation and segregation degree in the shell around the center of the wide and narrow sides were aggravated from 4.5 mm to 6.2 mm and from 0.84 to 0.738, respectively. With the rise of current intensity the bloom surface temperature, level fluctuation, stirring intensity, uniformity of molten steel temperature, and solute distribution also increased, while the growth velocity of the solidifying shell in the EMS effective zone declined and the solute mass fraction at the center of the computational outlet (z = 1.5 m) decreased. M-EMS with a current intensity of 600 A is more suitable for big bloom castings.

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“…The density ρ is assumed to be a constant except in the buoyancy terms according to the Boussinesq approximation [24].…”

Section: Turbulent Flowmentioning

confidence: 99%

Effects of EMS Induced Flow on Solidification and Solute Transport in Bloom Mold

Fang

Wang

et al. 2017

Metals

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“…The effects of the motion and the morphology of equiaxed grains on macrosegregation have been investigated in a 3.3 t ingot using a two-phase model by Combeau and coworkers. 6) Li et al 15) developed a two phase model to predict macrosegregation in a 53 t ingot, and comparisons were made between the predictions and measurements. Ludwig 16) applied a sophisticated three-phase model to predict the macrosegregation in a 2.45 t ingot.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, the two phase model developed by the authors 7,15) has been adopted to model the macrosegregation in a 231 t steel ingot. The simulation results are compared with the measurements in the plant.…”

Section: Introductionmentioning

confidence: 99%

Two-Phase Modeling of Macrosegregation in a 231 t Steel Ingot

Shen

Liu

2014

ISIJ Int.

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The formation of macrosegregation in the steel ingots is a multiphase/multiscale flow phenomenon inherently. It still remains a challenge to simulate the macrosegregation in the large steel ingots. The objective of this work is to validate a two phase model by measuring the macrosegregation in a 231 t steel ingot. The model incorporates the descriptions of heat transfer, melt convection, solute transport, and the solid movement on the system scale with microscopic relations for grain nucleation and growth. The model simulates the solidification process by solving the conservation equations of mass, momentum, energy and species for both the liquid and solid phases. Besides, simulations are performed to investigate the influence of the critical solid volume fraction (gsc) on the final macrosegregation pattern which was characterized by experimental measurements. It is indicated that the typical macrosegregation patterns encountered in a large steel ingot, including a positively segregated zone in the hot top and a negatively segregated zone in the bottom part of the ingot, are well reproduced with the current two phase model. Comparison of the simulation results and the measurements is made. It is demonstrated that the critical solid volume fraction gsc is an important factor for the final macrosegregation pattern.

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“…4) Li et al developed a twophase macrosegregation model that incorporates heat transfer, melt convection, solute transport, equiaxed grain motion, and grain nucleation and growth. 5) Nastec developed a generic framework studying macrosegregation in various casting processes using a computational fluid dynamics (CFD) code by solving the temperature, flow and solute balance in the multi-component alloy systems. 6) Hervé Combeau presented a multiphase and multi-scale model that describes the evolution of the morphology of the equiaxed crystals.…”

Section: Introductionmentioning

confidence: 99%

Water Analog Experimental Method for the Diffusion and Distribution of Alloy Elements in Liquid Steel during Ingot Filling Process

et al. 2014

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To physically simulate the alloy elements transportation and diffusion in the liquid steel during the making of heavy ingots, a water analogy experimental method is presented. In this method, methylene blue dye is used as solute to simulate the alloy element carbon in the melt steel. And a measurement method is proposed to measure the concentration of the solute, in which the laser reflection intensity detection method is used. The water analogy experiment setup is constructed. The multi-concentration pouring of a 438 t ingot is investigated by this method. The concentration of the ladles decrease with the pouring consequence. The concentration variation curves with time at the tundish outlet and in the mold are acquired and analyzed. The tundish outlet concentration decreases gradually and no fluctuation occurs during the change of ladles. Negative concentration gradient is achieved at the end of pouring, which can be helpful for controlling of the macrosegration usually occurring in the heavy ingot.

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Modelling of macrosegregation in steel ingots: benchmark validation and industrial application

Cited by 11 publications

References 10 publications

Effects of EMS Induced Flow on Solidification and Solute Transport in Bloom Mold

Effects of EMS Induced Flow on Solidification and Solute Transport in Bloom Mold

Two-Phase Modeling of Macrosegregation in a 231 t Steel Ingot

Water Analog Experimental Method for the Diffusion and Distribution of Alloy Elements in Liquid Steel during Ingot Filling Process

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