Effect of basicity and B2O3 on viscosity, melting and crystallization behaviors of low fluorine mold fluxes for casting medium carbon steels

Zhou, Lejun; Wang, Wanlin; Lu, Boxun; Wen, Guangrui; Yang, Jian

doi:10.1007/s12540-015-1015-7

Cited by 47 publications

(33 citation statements)

References 19 publications

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“…[25][26][27][28] And, it was divided into two parts; the first part is about melting and heat transfer behaviors; while the second part is focused on the study of viscosity and crystallization behavior of F-free mold fluxes for medium carbon steels continuous casting. This is the second part with the aim to investigate the viscosity and crystallization behavior of F-free mold fluxes.…”

Section: 24)mentioning

confidence: 99%

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

2015

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Viscosity and crystallization are essential properties to characterize the lubrication and heat transfer performances of mold flux. Therefore, in this paper, the viscosity and crystallization behaviors of conventional F-containing commercial mold flux and newly designed F-free mold fluxes were investigated by using rotating cylinder method and Single/Double Hot Thermocouple Technique (SHTT/DHTT). Results shows that the viscosities of designed F-free mold fluxes are close to the F-containing mold flux; and the crystallization temperatures of F-free mold fluxes increases with the increase of basicity and Na 2 O/Li 2 O content; while it decreases with the increase of cooling rate and the addition of B 2 O 3 . The final steady state structure of F-free mold fluxes during the DHTT tests shows it is composed of a major crystalline and a thin liquid layer (5.42-7.2%) without glass phase. The results of XRD indicate that the main crystalline phases formed in designed F-free mold fluxes were calcium borosilicate (Ca 11

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Section: 24)mentioning

confidence: 99%

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

2015

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“…A calibration measurement was carried out at room temperature by using stand oil with a known viscosity. [29] During the viscosity measurement test, first, about 250 g of the sample powders were placed in a graphite crucible with a diameter and internal height of 50 and 80 mm, respectively. Second, the crucible was heated to 1773 K (1500°C) and held for 10 minutes to obtain a homogeneous melt in an electric resistance furnace with MoSi 2 as the heating element.…”

Section: Lejun Zhou and Wanlin Wangmentioning

confidence: 99%

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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“…Thus, these fluorides will lead to the corrosion of equipment, serious environmental pollution, etc. [6,7] Therefore the development of new environmental friendly F-free mold fluxes is of great importance.…”

Section: Introductionmentioning

confidence: 99%

“…Nakada et al [3,7,8] studied the crystallization behaviors of CaO-SiO 2 -TiO 2 slag system and their results suggested that the precipitate CaOAESiO 2 AETiO 2 in the F-free mold flux could be a substitute for cuspidine. However, Wang et al found that the formation of the high melting point compounds such as TiN and Ti(C,N) in the liquid slag during the casting process may cause the increase of viscosity, break temperature, T br and crystallization temperature, which leads to a lack of lubrication and the tendency of sticker breakout.…”

Section: Introductionmentioning

confidence: 99%

Influences of Basicity and Li2O on the Properties of Fluorine-Free Mold Flux for the Casting of Medium Carbon Steels

Wang

Xiong

Zhou

et al. 2016

Metall Mater Trans B

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An investigation was carried out to study the influences of basicity and Li 2 O on the melting, crystallization, and heat transfer behavior of Fluorine-free mold flux designed for the casting of medium carbon steels using double hot thermocouple technology and infrared emitter technique. The results showed that with the addition of basicity, the melting and crystallization temperatures of the mold fluxes were increased, and the final heat transfer rate was reduced, as the basicity tends to promote the crystallization behavior of the designed mold fluxes. Besides, with the increase of Li 2 O content in the mold flux, the melting and crystallization temperature decreased, as the Li 2 O tends to inhibit the formation of high melting temperature crystal and lower the system melting temperature zone; meanwhile the crystallization capability of the mold flux was enhanced in the low-temperature region. Moreover, the results of EDS and XRD were confirmed that the main crystal phase in the Fluorine-free mold fluxes is calcium borate silicate (Ca 11 Si 4 B 2 O 22 ). Those results obtained can provide guidelines for the design of new Fluorine-free mold flux for the casting medium carbon steels.

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Effect of basicity and B2O3 on viscosity, melting and crystallization behaviors of low fluorine mold fluxes for casting medium carbon steels

Cited by 47 publications

References 19 publications

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

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

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

Influences of Basicity and Li2O on the Properties of Fluorine-Free Mold Flux for the Casting of Medium Carbon Steels

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