Influence of oxide scales on heat transfer in secondary cooling zones in the continuous casting process, part 2: determination of material properties of oxide scales on steel under spray‐water cooling conditions

Słowik, J.; Borchardt, Günter; Köhler, Christian; Jeschar, Rudolf; Scholz, Reinhard

doi:10.1002/srin.199000353

Cited by 36 publications

(21 citation statements)

References 6 publications

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“…For such mathematical simulations, the thermal conductivity and diffusivity of the iron oxide scale are the most important thermophysical properties. 4) To date, to the best of the authors' knowledge, there have been six reports on the thermal conductivity/diffusivity of iron oxide scales; [5][6][7][8][9][10] each has reported that the thermal conductivities/diffusivities of iron oxide scales are smaller than those of steel. Three of these studies have obtained the thermal diffusivities of single-phase samples of sintered iron oxides as functions of temperature.…”

Section: Introductionmentioning

confidence: 99%

“…Three of these studies have obtained the thermal diffusivities of single-phase samples of sintered iron oxides as functions of temperature. [5][6][7] However, there are large discrepancies between the values and temperature dependencies. With respect to FeO, for example, Slowik et al 5) and Akiyama et al 6) have reported that the thermal diffusivity shows a positive temperature dependence, whereas Takeda et al 7) find a negative temperature dependence.…”

Section: Introductionmentioning

confidence: 99%

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Temperature Dependence of Thermal Diffusivity and Conductivity of FeO Scale Produced on Iron by Thermal Oxidation

Endo

Akoshima³

et al. 2017

ISIJ International

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The thermal diffusivity/conductivity of FeO scales produced on iron substrates by thermal oxidation have been determined as functions of temperature. Iron plates (99.99%) were oxidised at 973 K in air to obtain oxide scales of FeO, Fe 3 O 4 , and Fe 2 O 3 , and then were reduced at 1 273 K in nitrogen to obtain FeO-only. The densities of these scales were 5.85-6.05 g cm − 3 . The laser flash method was used to measure the apparent thermal diffusivity of the whole sample from room temperature to 1 164 K during the heating/ cooling cycles. This was converted to the thermal diffusivity of the scale only, which in turn was converted to the thermal conductivity. However, these values depended on the scale thickness, which suggests an interfacial heat resistance occurs between the scale layer and iron substrate. In addition, scanning electron microscopy (SEM) observations revealed that the scales contained Fe and Fe 3 O 4 phases after heating. The scale thermal diffusivity/conductivity were corrected considering the interfacial heat resistance and dispersed phases to derive the corresponding values for FeO only. The interfacial heat resistance derived from the thickness dependence of the scale thermal conductivity was 8.3 × 10 − 6 m 2 K W − 1 . Using this value, the thermal diffusivity of FeO was derived as 3.7 × 10 − 7 -5.8 × 10 − 7 m 2 s − 1 and the thermal conductivity as 1.8-2.5 W m − 1 K − 1 between room temperature and 1 164 K. The temperature coefficients of the thermal conductivity were mostly negative, which would be dominated by the phonon mean free path.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temperature Dependence of Thermal Diffusivity and Conductivity of FeO Scale Produced on Iron by Thermal Oxidation

Endo

Akoshima³

et al. 2017

ISIJ International

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“…13) Taylor et al measured on FeO film with the thickness of 0.35 mm grown on a 1 mm-thick iron plate. Several other reports are also available about sintered samples of FeO, Fe3O4 and Fe2O3; [14][15][16][17] however, there are large discrepancies between the reported values. For example, the thermal diffusivity of FeO ranges from 4 to 7 × 10 -7 m 2 s -1 at room temperature.…”

Section: Introductionmentioning

confidence: 99%

“…For example, the thermal diffusivity of FeO ranges from 4 to 7 × 10 -7 m 2 s -1 at room temperature. 14,15) The difference might come from the difference in the sample preparation processes. Slowik et al 14) measured on sintered FeO samples with 32% porosity and estimated thermal diffusivities of FeO with no porosity.…”

Section: Introductionmentioning

confidence: 99%

Thermal Diffusivity Measurement of Oxide Scale Formed on Steel during Hot-rolling Process

et al. 2014

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Thermal diffusivity and conductivity of oxide scales formed on steel plates are essential to control the cooling rate of the steel in the hot-rolling process. A flash method was applied to measure the thermal diffusivity of oxide scales. Sample specimens were commercial hot-rolled plates on which about 25 μm-thick oxide scales were formed. The results of the flash measurement with the analysis for two-layered sample provided an average thermal diffusivity value of 7.3 × 10 -7 m 2 s -1 for the oxide scale. This value produces a thermal conductivity value of 3.8 W m -1 K -1 . The future application of this measurement and analysis technique was also discussed to derive the thermal diffusivity and conductivity of oxide scales formed in actual hot-rolling processes.

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“…Los mismos autores (25) encontraron además que, en el caso de mantenerse una película estable de vapor, la presencia de una capa de óxido modifica la transferencia de calor sólo cuando dicha capa se mantiene adherida a la superficie y cubriendo más de un 90 % de la misma. En tal circunstancia, se debe considerar la resistencia térmica aportada por el óxido (26).…”

Section: Enfriamiento Por La Acción Directa Del Aguaunclassified

Transferencia de calor en la colada continua de aceros. II parte. Enfriamiento secundario

Cicutti¹

1997

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REVISIÓNTransferencia de calor en la colada continua de aceros (#) II parte. Enfriamiento secundario C. Cicutti^Resumen La solidificación del acero iniciada en el molde continúa en la zona de enfriamiento secundario de la máquina donde el calor es extraído, principalmente por la incidencia del agua de los rociadores, la radiación al medio ambiente, el contacto con los rodillos y el agua acumulada en ellos. En este trabajo se revisa cada uno de estos mecanismos determinando, en los casos en que es posible, valores cuantitativos de los mismos. Además, se analizan los distintos métodos empleados para medir el avance del espesor solidificado en la máquina de colada continua. Por último, se discute la incidencia del enfriamiento secundario en la calidad final de los productos colados.Palabras clave: Colada continua. Aceros. Transferencia de calor. Enfriamiento secundario. Solidificación. Heat transfer in the continuous casting of steels Part 2. Secondary cooling AbstractOnce the strand leaves the mold, the solidification of steel progresses due to the heat extracted in the secondary cooling zone of the continuous casting machine. In this zone, heat is extracted mainly by: the incidence of water from sprays, radiation to surroundings contact with rolls and run out water accumulated between rolls and strand. In this work, all these mechanisms are evaluated and, when it is possible, they are quantified. Methods which are usually employed to measure solidification profiles in the continuous casting machine are also reviewed. Finally, the incidence of secondary cooling on the quality of cast products is discussed.

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Influence of oxide scales on heat transfer in secondary cooling zones in the continuous casting process, part 2: determination of material properties of oxide scales on steel under spray‐water cooling conditions

Cited by 36 publications

References 6 publications

Temperature Dependence of Thermal Diffusivity and Conductivity of FeO Scale Produced on Iron by Thermal Oxidation

Temperature Dependence of Thermal Diffusivity and Conductivity of FeO Scale Produced on Iron by Thermal Oxidation

Thermal Diffusivity Measurement of Oxide Scale Formed on Steel during Hot-rolling Process

Transferencia de calor en la colada continua de aceros. II parte. Enfriamiento secundario

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