Distribution and Detriment of Bubbles in Continuous Casting Interstitial Free Steel Slab

Wang, Min; Bao, Yanping; Zhao, Lihua; Yang, Quan; Li, Lin

doi:10.2355/isijinternational.55.799

Cited by 12 publications

(7 citation statements)

References 10 publications

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“…For clean steel production, it is highly important to investigate the distribution of the inclusions and argon bubbles in the slabs. The particle distributions of the slabs have been studied by both experimental measurements [3][4][5][17][18][19][20] and numerical simulations. [16,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Due to the limitations for scope and accuracy of the instruments used for the detection of particles in the slabs, the measurements of particle distributions in the slab are usually not comprehensive.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Transient Flow, Particle Transport, and Entrapment in Slab Mold with Double‐Ruler Electromagnetic Braking

Yin

Zhang

et al. 2021

steel research int.

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To study the transient transport and capture of inclusions and argon bubbles simultaneously in slab mold with double-ruler electromagnetic braking (EMBr), a transient large eddy simulation model coupling molten steel flow, solidification, electromagnetic field, and particle motion is constructed. In this model, momentum transfer between argon bubbles and molten steel is implemented by two-way coupling. The results indicate that the EMBr changes the molten steel transient flow pattern in the liquid pool. Due to the braking effect, the asymmetry and instability of the molten steel transient flow are weakened. Moreover, EMBr changes the transient particle (inclusion and argon bubble) transports inside the liquid pool. The particle motions inside the liquid pool are constrained, and the dispersion of the particles inside the liquid pool is weakened by EMBr. In addition, the contents of particles within the slab surface layer are decreased under the application of EMBr. Nevertheless, in the slab interior, the contents of the particles under the application of EMBr are higher than those in the absence of EMBr.

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Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Transient Flow, Particle Transport, and Entrapment in Slab Mold with Double‐Ruler Electromagnetic Braking

Yin

Zhang

et al. 2021

steel research int.

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“…A few previous studies have measured bubble distributions in the final solidified slab. [28][29][30] Other studies have measured air-bubble size distributions in the nozzle 20,[31][32][33] and mold [34][35][36][37][38][39] during casting, using water model experiments and mathematical modeling. The average bubble size ranges from 2-6 mm initial diameter, 0.5-3.5 mm inside the SEN, and 1-3 mm in the mold, for various conditions including water and air flow rates and geometries.…”

Section: Introductionmentioning

confidence: 99%

Bubble Behavior and Size Distributions in Stopper-Rod Nozzle and Mold during Continuous Casting of Steel Slabs

2018

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Argon-gas injection parameters including flow rate and bubble size distribution are important to prevent nozzle clogging, control the mold flow, and reduce bubble-related defects in steel continuous casting. This work employs water-air model experiments and analytical modeling to quantify the behavior and size distributions of gas bubbles in the nozzle and mold during nominally steady-state slab-casting, focusing on gas injection through a stopper-rod with multiple side-channels. Bubble formation, breakup, coalescence, and accumulation are investigated with experiments using a one-third scale water model with the aid of high-speed video recording and analytical models to predict gas pressure, initial bubble size, bubble descending velocity, bubble residence time, and bubble size distribution considering accumulation. In addition, size distributions of the bubbles in the nozzle and mold are quantified by analyzing snapshots of bubble images. Bubbles initiate at the gas channel exit in the stopper-rod after overcoming the pressure threshold, and then expand and elongate until detaching from the stopper-rod surface. After that, turbulent flow breaks up the bubbles inside the gap between the stopper-rod and the nozzle inlet. The bubbles sometimes coalesce with others, and get bigger while flowing down through the nozzle. The bigger bubbles have longer residence time, and accumulate in the nozzle, due to higher buoyancy on them. With higher gas flow-rate, bubble size distribution in the nozzle and mold shows larger average-size and broader size-range. Finally, the validated initial bubble-size model with the water-air model measurements is extrapolated to estimate argon-bubble sizes in molten steel with real caster conditions.

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“…Subsurface hooks are often accompanied by deep oscillation marks (OMs) for ultra-low carbon steels because of the high liquid line temperature and thin mushy zone of ultralow carbon steels during solidification inside a continuous casting mold [1][2][3][4]. For interstitial-free (IF) steel, a type of ultra-low carbon steel, severe subsurface hooks degrade the slab surface quality because of the entrapment of inclusions (e.g., argon bubbles and alumina-type inclusions) by hooks, which leads to the generation of sliver and blister defects on the surface of the final cold-rolled strip products [5][6][7]. Therefore, a better understanding of the entrapment mechanism of the subsurface is needed to improve the surface quality of steel slabs.…”

Section: Introductionmentioning

confidence: 99%

Hook evolution and inclusion entrapment during initial solidification process of continuous casting slab

Ping

Zhu

et al. 2018

Metall. Res. Technol.

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A two-dimensional numerical model was established to describe the mechanism of hook formation and evolution during the initial solidification process of continuous casting slab. Melting, coarsening, growing, and burying stages were observed to follow hook formation at the meniscus. The coordinates at which the hook was finally buried into the shell were determined for different casting speeds and pouring temperatures. The final hook depth was predicted to be approximately 1.8-2.9 mm, which was confirmed by metallographic experiments. A physical model was established based on the calculated shell shape, and the process by which the inclusions were entrapped by the hook structure was investigated. The results indicated that the floating inclusions were most likely entrapped under the nascent hook, and the inclusions gathering near the meniscus were easily captured by the upper part of the nascent hook when overflow of the molten steel occurred. The hooklike structure increased the area of the shell inner face, which resulted in swirling flow of the molten steel near the shell and increased the probability of the inclusions being captured.

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Distribution and Detriment of Bubbles in Continuous Casting Interstitial Free Steel Slab

Cited by 12 publications

References 10 publications

Large Eddy Simulation of Transient Flow, Particle Transport, and Entrapment in Slab Mold with Double‐Ruler Electromagnetic Braking

Large Eddy Simulation of Transient Flow, Particle Transport, and Entrapment in Slab Mold with Double‐Ruler Electromagnetic Braking

Bubble Behavior and Size Distributions in Stopper-Rod Nozzle and Mold during Continuous Casting of Steel Slabs

Hook evolution and inclusion entrapment during initial solidification process of continuous casting slab

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