Multiphase Flow-Related Defects in Continuous Casting of Steel Slabs

Cho, Seong‐Mook; Liang, Mingyi; Olia, Hamed; Das, Lipsa; Thomas, Brian G.

doi:10.1007/978-3-030-36296-6_108

Cited by 10 publications

(4 citation statements)

References 17 publications

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“…Particles entering the mold may be safely removed into the surface slag layers or captured into the steel shell in three different ways: (1) entrapment by subsurface hooks near the top surface [6,7], (2) entrapment by moving in between solidifying dendrites according to the Primary Dendrite Arm Spacing (PDAS), or (3) engulfment by balancing at the steel shell solidification front and then being surrounded by the growing dendrites. Once particles are captured into the steel shell, and are not removed by scale formation or scarfing processes, they eventually become defects, such as blisters and/or slivers in the final steel products after annealing and rolling processes [8]. Thus, it is important to understand the complex phenomena of particle transport and capture in the mold and strand regions, and to minimize such defects by controlling the system geometry, fluid flow, and casting conditions.…”

Section: Introductionmentioning

confidence: 99%

Modeling of Inclusion Capture in a Steel Slab Caster with Vertical Section and Bending

Cho

Thomas

Hwang

et al. 2021

Metals

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Particles in molten steel, including argon-gas bubbles, slag droplets, and non-metallic inclusions, are removed into the surface-slag layer or captured by the solidifying steel-shell during continuous steel casting. Captured particles often become serious defects in the final steel product, so understanding particle-capture mechanisms is important for steel quality. Slab casters often have a straight mold and upper-strand prior to a curved lower-strand. The present work investigates particle capture in such a caster using computational modeling with a standard k-ε model for molten-steel flow, a discrete phase model for inclusion transport, and an advanced capture criterion for inclusion entrapment and engulfment into the steel shell. A new postprocessing methodology is presented and applied to predict inclusion-capture rates in commercial cast product. The locations and size distributions of particles captured into the shell, and actual capture rates are quantified. The model predictions are validated with ultrasonic-test plant measurements of the locations of large particles captured in a steel slab. The results reveal how large-inclusion capture accumulates in the beginning of the curved strand, leading to a capture band in the slab inside radius. Finally, the capture fractions and locations due to all capture mechanisms are compared for different inclusion sizes, and the implications are discussed.

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Section: Introductionmentioning

confidence: 99%

Modeling of Inclusion Capture in a Steel Slab Caster with Vertical Section and Bending

Cho

Thomas

Hwang

et al. 2021

Metals

Self Cite

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“…The Poisson equation for the electric potential u Eq. [8] is split for the melt and the solid regions. For the liquid bulk it becomes the following:…”

Section: Modeling a Conductive Solidmentioning

confidence: 99%

“…The formation mechanisms of the multiphase flow-related defects, the corresponding high-resolution numerical models to quantify them and the control technique involving applying electromagnetic forces are discussed by Cho et al [8] A correct prediction of the multiphase flows strongly depends on the turbulence modeling. For numerical simulations on an industrial scale, a compromise between the accuracy and robustness of the algorithm is always desired.…”

Section: Introductionmentioning

confidence: 99%

Electric Current Distribution During Electromagnetic Braking in Continuous Casting

Vakhrushev

Kharicha

Liu

et al. 2020

Metall Mater Trans B

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The electromagnetic brake (EMBr) is a well-known and widely applied technology for controlling the melt flow in the continuous casting (CC) of the steel. The effect of a steady (DC) magnetic field (0.31 T) in a CC mold is numerically studied based on the GaInSn experiment. The electrical boundary conditions are varied by considering a perfectly insulating/conductive mold or the presence of a conductive solid shell, which is experimentally modeled by 0.5 mm brass plates. An intense current density (up to 350 kA/m 2) is induced by the EMBr magnetic field in the form of loops. The electric current loop tends to close either inside the liquid bulk or through the conductive solid. Based on the character of the induced current loop closures, the turbulent flow is affected as follows: (i) it becomes unstable in the insulated mold, forming 2D self-inducing vortex structures aligned with the magnetic field; (ii) it is strongly damped for the conductive mold; and (iii) it exhibits transitional behavior with the presence of a solid shell. The application of the obtained results for the real CC process is discussed and validated.

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“…Free surface behavior, slag/gas bubble entrapment issue, etc., are of immense importance [41][42][43]. Both experimental work and advanced model development have been the topics of recent research [44][45][46][47][48].…”

Section: Introductionmentioning

confidence: 99%

On Modelling Parasitic Solidification Due to Heat Loss at Submerged Entry Nozzle Region of Continuous Casting Mold

Vakhrushev

Kharicha

et al. 2021

Metals

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Continuous casting (CC) is one of the most important processes of steel production; it features a high production rate and close to the net shape. The quality improvement of final CC products is an important goal of scientific research. One of the defining issues of this goal is the stability of the casting process. The clogging of submerged entry nozzles (SENs) typically results in asymmetric mold flow, uneven solidification, meniscus fluctuations, and possible slag entrapment. Analyses of retained SENs have evidenced the solidification of entrapped melt inside clog material. The experimental study of these phenomena has significant difficulties that make numerical simulation a perfect investigation tool. In the present study, verified 2D simulations were performed with an advanced multi-material model based on a newly presented single mesh approach for the liquid and solid regions. Implemented as an in-house code using the OpenFOAM finite volume method libraries, it aggregated the liquid melt flow, solidification of the steel, and heat transfer through the refractory SENs, copper mold plates, and the slag layer, including its convection. The introduced novel technique dynamically couples the momentum at the steel/slag interface without complex multi-phase interface tracking. The following scenarios were studied: (i) SEN with proper fiber insulation, (ii) partial damage of SEN insulation, and (iii) complete damage of SEN insulation. A uniform 12 mm clog layer with 45% entrapped liquid steel was additionally considered. The simulations showed that parasitic solidification occurred inside an SEN bore with partially or completely absent insulation. SEN clogging was found to promote the solidification of the entrapped melt; without SEN insulation, it could overgrow the clogged region. The jet flow was shown to be accelerated due to the combined effect of the clogging and parasitic solidification; simultaneously, the superheat transport was impaired inside the mold cavity.

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Multiphase Flow-Related Defects in Continuous Casting of Steel Slabs

Cited by 10 publications

References 17 publications

Modeling of Inclusion Capture in a Steel Slab Caster with Vertical Section and Bending

Modeling of Inclusion Capture in a Steel Slab Caster with Vertical Section and Bending

Electric Current Distribution During Electromagnetic Braking in Continuous Casting

On Modelling Parasitic Solidification Due to Heat Loss at Submerged Entry Nozzle Region of Continuous Casting Mold

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