Viscosity and Crystallization Behavior of F-free Mold Flux for Casting Medium Carbon Steels

Zhou, Lejun; Wang, Wanlin; Zhou, Kechao

doi:10.2355/isijinternational.isijint-2015-193

Cited by 46 publications

(45 citation statements)

References 29 publications

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“…However, the viscosity of mold flux decreases slowly with the increase of temperature in the high-temperature zone, while it increased sharply with the reduction of temperature in the lower temperature zone, which indicates that logg vs T is obviously nonlinear related in the whole temperature range. Actually, in our previous paper, [7] to study the rheological behavior of F-free mold flux, the whole temperature range was divided into two temperature zone, one is the temperature below break temperature (T <T br ) and the other is T>T br . Then, the logg vs T fitted by the Arrhenius model should be separated in two temperature zones.…”

Section: Lejun Zhou and Wanlin Wangmentioning

confidence: 99%

“…The data, derived from these restricted ranges of experimental conditions, were generally linear in reciprocal of temperatures; thus, the early models follow Arrhenius formulation strictly. [6][7][8] But, the mold flux in a continuous casting mold experiences a wider temperature gradient from more than 1773 K (1500°C) to room temperature. [9,10] For the mold flux on top of the molten steel, its temperature is close to the molten steel, while its temperature decreases to break temperature after the liquid mold flux infiltrates into the gap between the mold wall and the shell; its temperature further decreases to room temperature as the mold flux comes out with the slab from the bottom of the mold.…”

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confidence: 99%

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Application of Non-Arrhenius Models to the Viscosity of Mold Flux

Zhou

Wang

2016

Metall Mater Trans B

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The mold flux in continuous casting mold experiences a significant temperature gradient ranging from more than 1773 K (1500°C) to room temperature, and the viscosity of the mold flux would therefore have a nonArrhenius temperature dependency in such a wide temperature region. Three non-Arrhenius models, including Vogel-Fulcher-Tammann (VFT), Adam and Gibbs (AG), and Avramov (AV), were conducted to describe the relationship between the viscosity and temperature of mold flux in the temperature gradient existing in the casting mold. It found that the results predicted by the VFT and AG models are closer to the measured ones than those by the AV model and that they are much better than the Arrhenius model in characterizing the variation of viscosity of mold flux vs temperature. In addition, the VFT temperature and AG temperature can be considered to be key benchmarks in characterizing the lubrication ability of mold flux beyond the break temperature and glass transition temperature.Viscosity is one of the most important properties of mold flux as it determines the powder consumption and therefore the lubrication of the shell; [1,2] it also affects the formation of the slag rim in the vicinity of the meniscus, [3] the slag entrapment, [4] as well as the erosion of the nozzle. [5] Early models for predicting the viscosity of mold flux were developed by using viscosity measurements that spanned relatively small ranges of temperature and viscosity. The data, derived from these restricted ranges of experimental conditions, were generally linear in reciprocal of temperatures; thus, the early models follow Arrhenius formulation strictly. [6][7][8] But, the mold flux in a continuous casting mold experiences a wider temperature gradient from more than 1773 K (1500°C) to room temperature. [9,10] For the mold flux on top of the molten steel, its temperature is close to the molten steel, while its temperature decreases to break temperature after the liquid mold flux infiltrates into the gap between the mold wall and the shell; its temperature further decreases to room temperature as the mold flux comes out with the slab from the bottom of the mold. The mold flux viscosity does not show strong Arrhenius dependency over such wide temperature variation.There are three models developed for description of the non-Arrhenius temperature-dependent viscosity in silicate melts, including Vogel-Fulcher-Tammann (VFT), Adam and Gibbs (AG), and Avramov (AV).The Vogel-Fulcher-Tammann (VFT) model was proposed by Vogel, Fulcher, and Tammann, [11][12][13] and it has been widely used to estimate the variation of viscosity of magma, [14,15] glass-forming liquids, [16] polymers, [17] ceramics, [18] ionic liquids, [19] etc. It was expressed as:where g is the viscosity in Pa s and T is the absolute temperature (K). The variables A VFT , B VFT , and C VFT are adjustable parameters representing the pre-exponential factor, the pseudo-activation energy, and the VFT temperature, respectively.The Adam-Gibbs model [20] is the result of a generalization and a...

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Section: Lejun Zhou and Wanlin Wangmentioning

confidence: 99%

mentioning

confidence: 99%

Application of Non-Arrhenius Models to the Viscosity of Mold Flux

Zhou

Wang

2016

Metall Mater Trans B

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“…Numerous studies on the crystallization behavior of oxide melts conducted by various methods including differential thermal analysis, 21) scanning electron microscopy, and X-ray diffraction (XRD) 22,23) have been reported. Crystallinity of the prepared samples is usually quantified by either quenching them at particular temperatures followed by polishing with epoxy resins and subsequent microscopic observations or by utilizing internal standards during XRD measurements.…”

Section: Crystallinity Of Supercooled Oxide Melts Quantified By Electmentioning

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Crystallinity of Supercooled Oxide Melts Quantified by Electrical Capacitance Measurements

2017

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“…Details about the SHTT apparatus have been illustrated by Prof. Kashiwaya [17] and our previous paper [18]. Figure 6 shows the schematic of the SHTT experimental apparatus.…”

Section: The Initial Crystallization Temperature Testmentioning

confidence: 99%

A Study of the Heat Transfer Behavior of Mold Fluxes with Different Amounts of Al2O3

Zhou

Wang

Zhou

2016

Metals

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Abstract:The element Al in molten aluminum containing steel reacts with the liquid mold flux and thus be transferred into the mold flux during the continuous casting process. Additionally, the increase in alumina in a mold flux changes its performance significantly. Thus, in this paper, the heat transfer properties of mold fluxes with the Al 2 O 3 content ranging from 7 to 40 wt. % were studied with the Infrared Emitter Technique (IET). Results found that heat flux at the final steady state decreased from 423 kW¨m´2 to 372 kW¨m´2 with the increase in Al 2 O 3 content from 7% to 30%, but it increased to 383 kW¨m´2 when the Al 2 O 3 content was further increased to 40%. Both crystalline layer thickness and crystalline fraction first increased, then decreased with the further addition of A 2 O 3 content. Moreover, it indicated that the heat transfer process inside the mold was dominated by both a crystallization of mold flux and the resulting interfacial thermal resistance. Further, the R int increased from 9.2ˆ10´4 m 2¨k W´1 to 11.0ˆ10´4 m 2¨k W´1 and then to 16.0ˆ10´4 m 2¨k W´1 when the addition of Al 2 O 3 content increased from 7% to 20% and then to 30%, respectively; however, it decreased to 13.6ˆ10´4 m 2¨k W´1 when the Al 2 O 3 content reached 40%.

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Viscosity and Crystallization Behavior of F-free Mold Flux for Casting Medium Carbon Steels

Cited by 46 publications

References 29 publications

Application of Non-Arrhenius Models to the Viscosity of Mold Flux

Application of Non-Arrhenius Models to the Viscosity of Mold Flux

Crystallinity of Supercooled Oxide Melts Quantified by Electrical Capacitance Measurements

A Study of the Heat Transfer Behavior of Mold Fluxes with Different Amounts of Al2O3

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