Heat flow, gap formation and break-outs in the continuous casting of steel slabs

Grill, A.; Sorimachi, Kenichi; Brimacombe, J. K.

doi:10.1007/bf02654916

Cited by 90 publications

(50 citation statements)

References 5 publications

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“…Several of these are believed to arise in the early stage of solidification in the mold. Over the years, many mathematical models have been developed to investigate the origin of these defects, [7][8][9][10][11][12][13][14][15] since experimental measurements of stresses or strains during solidification are nearly impossible. Exact analytical solutions in a one-dimensional model for the thermal stress arising during solidification of the casting were derived by several researchers.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Gap Formation at Mold-Shell Interface during Solidification of Aluminum Alloy Plate

Kim

2003

ISIJ International

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Thermal contraction of the casting and the thermal expansion of the mold result in gap formation at the mold-casting interface, which affects greatly the heat transfer between the mold and casting. Information on the movements of the mold and casting during solidification and cooling is also the basis for the investigation of the casting deformation.Movements of the casting and mold were analyzed simultaneously using coupled thermo-mechanical contact boundary model for the plate casting of aluminum alloy. The calculated displacement and temperature distributions of the casting and mold were compared with the previous measured data. It was confirmed that the mold and the casting moved together until the air gap formed by the calculation. Comparing the air gap curve with the displacement curve of the casting just before and after air gap formation made it apparent that the growth of the air gap was mainly due to contraction of the casting because the change in the mold displacement was not significant. Gap formation time increased with increase in initial mold temperature.KEY WORDS: coupled thermo-mechanical contact boundary model; air gap formation; mold bending; plate casting; mold and casting displacement.boundary model for the aluminum alloy plate casting. Figure 1 shows the meshes of the mold and of the casting used for thermal and stress analysis, performed by twodimensional thermo-mechanical coupled analysis. Half of the transverse section at the mid-height of the mold and casting was chosen for analysis. Dimensions of the casting were 100 mm wide by 12.5 mm thick, and the mold 150 mm wide by 37.5 mm thick. Size and shape of the casting and mold were chosen to compare the calculated results in the present study with the measured ones in the previous papers. 2,6,21,23,25) Each number in the figure shows locations where temperature and displacement are checked. Location 2 and 3 in the figure look like the same node, but two nodes are overlapped. Computational Procedure Model DescriptionA four-node quadrilateral element was used, one mesh being 2.5 by 1.25 mm for the mold, and 3.3 by 2.5 mm for the casting. The mold material was cast iron, the cast alloy being Al-7%Si-0.3%Mg alloy. Casting was treated as an elastic-plastic deformable body, mold as an elastic deformable one and plane strain was assumed.Mold material properties were assumed to be constant independent of temperature. Casting material properties were temperature dependent. Thermal conductivity and modulus of elasticity with temperature are given in Tables 1 and 2. 21) Density of the casting is 2 700 kg/m 3 . The latent heat was converted into the change of specific heat over the solidification range. However Al-7%Si-0.3%Mg alloy includes eutectic, latent heat during primary and eutectic solidification was evaluated using the ratio measured by a differential scanning calorimeter. In eutectic solidification, a temperature of 1 K was set as the range for latent release.Constant linear thermal contraction during solidification of the cast metal was co...

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Section: Introductionmentioning

confidence: 99%

Analysis of Gap Formation at Mold-Shell Interface during Solidification of Aluminum Alloy Plate

Kim

2003

ISIJ International

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“…Se han propuesto distintas aproximaciones para estudiar su formación y la relación con la aparición de defectos en el material (43)(44)(45)(46).…”

Section: Conducción Del Calor En La Capa De Acero Solidificadaunclassified

Transferencia de calor en la colada continua de aceros. I parte. El molde

Cicutti¹

1997

REVMETAL

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REVISIÓNTransferencia de calor en la colada continua de aceros (#) I parte. El molde C. Cicutti^Resumen El molde de colada continua cumple la importante función de recibir el acero líquido y permitir que se desarrolle una capa solidificada uniforme y libre de defectos. En este trabajo se revisan los distintos mecanismos implicados en el proceso de transferencia de calor, desde el acero líquido hasta el agua de refrigeración del molde. Se analiza también el efecto de las distintas variables de funcionamiento en la extracción calórica producida y la relación entre el flujo global de calor y su distribución a lo largo del molde.Palabras clave: Colada continua. Aceros. Transferencia de calor. Molde. Solidificación.Heat transfer in the continuous casting of steels Part 1. The mold AbstractThe continuous casting mold plays the important role of receiving the liquid steel and allowing an uniform and defect free solidified skin to be developed. In this work, the different heat transfer mechanisms which are present from the liquid steel to the mold cooling water are reviewed. The effect of operating variables on heat extraction and the relationship between global and distributed heat flux are also analyzed.

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“…[1] On the other hand, insufficient heat removal may lead to relatively frail spots in the shell that could culminate in breakouts. [2] Rejection or reconditioning of cracked slabs causes considerable economic losses, [3] and slab breakouts are major upsets, which bring about safety hazards, machine damage, and line stoppages. [4] Thus, heat transfer from the shell to the mold must match the operating conditions, e.g., steel composition, casting speed, and mold design, by choosing the mold powder that has adequate crystallization tendency, solidification temperature, and effective (phononic plus photonic) thermal conductivity, and that produces a slag film and solid slag layer-mold gap with the right thicknesses.…”

Section: Introductionmentioning

confidence: 99%

Study of Shell-Mold Thermal Resistance: Laboratory Measurements, Estimation from Compact Strip Production Plant Data, and Observation of Simulated Flux-Mold Interface

Flores

2016

Metall Mater Trans B

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The slag film that forms between the shell and mold in steel continuous casting is key in regulating the heat transfer between them. Generally, the mechanisms proposed are related to the phenomena associated with the formation of crystals in the solid layer of the film, such as the appearance of internal pores and surface roughness, which decrease phononic conduction through the layer and interfacial gap with the mold, respectively, and the emergence of crystals themselves, which reduce the transmissivity of infrared radiation across the layer. Due to the importance of the solid layer, this study investigates experimentally the effective thermal resistance, R T , between a hot Inconel surface and a cold Cu surface separated by an initially glassy slag disk, made from powders for casting low and medium-carbon steels, denoted as A and B, respectively. In the tests, an initially mirror-polished disk is sandwiched for 10,800 seconds while the Inconel temperature, away from the disk face, is maintained steady at a value, T c , between 973 K and 1423 K (700°C and 1150°C)-below the liquidus temperature of the slags. The disks have a thickness, d t , between~0.7 and 3.2 mm. Over the range of conditions studied, mold slag B shows R T 33 pct larger than slag A, and microscopic observation of disks hints that the greater resistance arises from the larger porosity developed in B. This finding is supported by high-temperature confocal laser scanning microscope observations of the evolution of the surface of slag parallelepipeds encased between Pt sheets, which reveal that during devitrification the film surface moves outward not inward, contrary with what is widely claimed. This behavior would favor contact of the slag with the mold for both kinds of powders. However, in the case of slag A, the crystalline grains growing at or near the surface pack closely together, leaving only few and small empty spaces. In slag B, crystalline grains pack loosely and many and large empty spaces arise in and below the surface. Estimation from plant data shows R T values smaller than measured ones, suggesting that the process film slag thickness must be considerably thinner than those of laboratory disks. However, the difference in thermal resistance of both powders, averaged over the mold length, is close to the dissimilarity found in laboratory.

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Heat flow, gap formation and break-outs in the continuous casting of steel slabs

Cited by 90 publications

References 5 publications

Analysis of Gap Formation at Mold-Shell Interface during Solidification of Aluminum Alloy Plate

Analysis of Gap Formation at Mold-Shell Interface during Solidification of Aluminum Alloy Plate

Transferencia de calor en la colada continua de aceros. I parte. El molde

Study of Shell-Mold Thermal Resistance: Laboratory Measurements, Estimation from Compact Strip Production Plant Data, and Observation of Simulated Flux-Mold Interface

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