Quantitative Model to Determine Permeability for Columnar Dendritic Structures

Natsume, Yukinobu; Takahashi, Daiki; Kawashima, Kasumi; Tanigawa, Eiji; Ohsasa, Kenichi

doi:10.2355/isijinternational.53.838

Cited by 23 publications

(9 citation statements)

References 28 publications

(93 reference statements)

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“…When the strand is continuously withdrawn from the copper mold, the columnar dendrite grows from the billet surface without moving with the liquid metal, as shown in Figure a, therefore it is reasonable to treat the columnar dendrite zone as a porous medium. The permeability of fluid flow parallel or normal to primary dendrite arms has been confirmed by many reaserchers, such as Santos and Melo, Bhat et al and Natsume et al Since the solidification shrinkage is not considered in the calcualtion, the peremeability of fluid flow normal to primary dendrite arms is determined by Equation , where λ 1 and λ 2 are primary and secondary arm spacing measured through the billet etched samples. The thicknesses of columnar and equiaxed dendrite zone are about 28 and 104 mm, respectively.…”

Section: Mathematical Modelmentioning

confidence: 88%

“…The columnar zone and equiaxed zone are distinguished by the etched microstructure of samples and are treated separately. The columnar dendrite region is treated as a porous zone and a generalized approach, which depended on the primary and secondary arm spacing is used to calculate permeability . As the initial growing crystal can move freely with the liquid in equiaxed dendrite zone, a variable apparent viscosity model is used to simulate the fluid flow.…”

Section: Introductionmentioning

confidence: 99%

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Flow and Solidification in Billet Continuous Casting Machine with Dual Electromagnetic Stirrings of Mold and the Final Solidification

Jiang

Zhu

2014

steel research int.

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A 3D numerical model coupling the electromagnetic field, fluid flow, heat transfer and solidification phenomena was developed to simulate the 160 mm Â 160 mm billet continuous casting process of SWRT82B steel with dual electromagnetic stirrings of mold and the final solidification. The columnar region was treated as a porous zone and a generalized approach was used to calculate permeability, while for the equiaxed zone, a variable apparent viscosity model was applied to simulate the fluid flow at the initial growing stage of equiaxed dendrite. The model was validated by the measured data of magnetic induction intensity in the stirrer center and strand surface temperature. The results show that it is indispensable to consider the solidification phenomenon in the mold zone with EMS, as the fluid flow mechanism near the meniscus is quite different. With the current intensity of M-EMS and F-EMS increasing, the tangential velocity of molten steel rises and the central temperature decreases. As the F-EMS is applied, the nature convection mechanism is destroyed and the temperature is promoted to distribute evenly in the mushy zone. Moreover, the results show that the coherent solid fraction has a significant effect on the temperature distribution and the fluid flow in F-EMS zone.

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Section: Mathematical Modelmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Flow and Solidification in Billet Continuous Casting Machine with Dual Electromagnetic Stirrings of Mold and the Final Solidification

Jiang

Zhu

2014

steel research int.

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“…As shown above, our large‐scale phase‐field lattice Boltzmann simulation enabled multiple dendrite growth with melt flow. It may have a potential for computing the permeability for the flow in the realistic solidification structure with multiple dendrites.…”

Section: Large‐scale Phase‐field Simulation Of Solidification and Gramentioning

confidence: 99%

Advent of Cross‐Scale Modeling: High‐Performance Computing of Solidification and Grain Growth

Shibuta

Ohno

Takaki

2018

Advcd Theory and Sims

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The application range of computational metallurgy is rapidly expanding thanks to the recent progress in high-performance computing. In this Progress Report, state-of-the-art collections of large-scale simulations of solidification and grain growth, performed on the GPU supercomputer, are introduced. One of the notable achievements in this direction is a billion-atom molecular dynamics simulation for nucleation and solidification, which revealed the heterogeneity in homogeneous nucleation. Moreover, a series of large-scale phase-field simulations shed light on the topics at issue including competitive growth of dendrites during the directional solidification, the effect of forced and natural convections on the solidification, and so on. Based on simulation results bridging the gap between atomistic and continuum-based simulations, a new criterion of multi-scale modeling is proposed in the age to come. We are now standing at the new era of cross-scale modeling, in which the overlap between atomistic and continuum simulations creates new research concepts and fields.

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“…[1][2][3][4] According to the antiparallel relationship between the growth direction of columnar dendrites and the heat flow direction and the upstream growth characteristic, the cooling uniformity and the intensity of electromagnetic stirring (EMS) can be deduced from the growth direction of columnar dendrites in the transverse section of strands. Meanwhile, the dendritic solidification parameters reflecting the cooling intensity, such as primary and secondary dendrite arm spacings, are important to predict the crack susceptibility of steel [5] and the permeability of the mushy zone, [6] which is crucial to accurately investigate the formation and the development of central macrosegregation. Therefore, investigation of the dendritic growth of continuously cast steel strands is helpful to understand the formation mechanism of solidification defects and improve the solidification quality of steel.…”

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Dendritic Growth of Continuously Cast High Carbon Steel

Wang

Luo

Zhu

2014

Metall Mater Trans A

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Considering the influence of the latent heat released during the solidification of high carbon liquid steel, a cellular automaton (CA) model coupled with the heat transfer was developed to investigate the growth of equiaxed dendrites which is controlled by the solute diffusion during the continuous casting process. Additionally, the growth of columnar dendrites and primary dendrite arm spacings were predicted and measured. The results show that the CA model is able to describe the growth behavior of equiaxed dendrites, especially at 5 K to 7 K melt undercoolings, and the approach adjusting the cooling medium temperature is reliable to keep the undercooling condition stable for equiaxed dendrites although its hysteresis is reinforced as the pre-set undercooling increases. With the increase of the melt undercooling, the growth of equiaxed dendrites becomes faster, and the thickness of dendritic arms increases slightly, however, the thickness of the diffusion layer in front of dendritic tips keeps constant. The growth of thin and tiny columnar dendrites will be confined due to the competition and absorbed by neighboring strong columnar dendrites, giving rise to the coarsening of columnar dendrites, which is observed both from the experimental observation and the numerical simulation. With the decrease of the cooling intensity, columnar dendrites get sparser, primary dendrite arm spacings increase, and secondary dendritic arms become undeveloped.

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Quantitative Model to Determine Permeability for Columnar Dendritic Structures

Cited by 23 publications

References 28 publications

Flow and Solidification in Billet Continuous Casting Machine with Dual Electromagnetic Stirrings of Mold and the Final Solidification

Flow and Solidification in Billet Continuous Casting Machine with Dual Electromagnetic Stirrings of Mold and the Final Solidification

Advent of Cross‐Scale Modeling: High‐Performance Computing of Solidification and Grain Growth

Numerical Simulation of Dendritic Growth of Continuously Cast High Carbon Steel

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