Thermal Resistance at the Interface between Mold Flux Film and Mold for Continuous Casting of Steels.

Cho, Jung‐Wook; Shibata, Hiroyuki; Emi, Toshihiko; Suzuki, Mikio

doi:10.2355/isijinternational.38.440

Cited by 138 publications

(125 citation statements)

References 1 publication

Supporting

Mentioning

116

Contrasting

Unclassified

Order By: Relevance

“…A crystalline layer in slag film yields larger thermal resistance by producing air gap at the flux/mold interface and scattering infrared radiation from steel. [3][4][5][6][7][8] The authors have focused on the compound, cuspidine (3CaO · 2SiO 2 · CaF 2 ), which crystallizes in the crystalline layer in flux films. [9][10][11] Since cuspidine primarily crystallizes in almost all of commercial mold fluxes, controlling the crystallinity is a key factor to control the horizontal heat flux.…”

Section: Introductionmentioning

confidence: 99%

Stability of Cuspidine (3CaO 2SiO2 CaF2) and Phase Relations in the CaO-SiO2-CaF2 System.

2002

View full text Add to dashboard Cite

Primary crystallization field of cuspidine (3CaO · 2SiO 2 · CaF 2 ) has been experimentally determined in the 2CaO · SiO 2 -SiO 2 -CaF 2 system by quenching method and differential thermal analysis (DTA). Hermetically closed platinum capsules were used as a sample container to prevent fluorine loss in the form of HF and SiF 4 by reaction of CaF 2 with moisture or SiO 2 for quenching experiments. Combining the present study with the partial phase diagrams previously reported, the whole phase diagram of the CaO-SiO 2 -CaF 2 system has been developed. Cuspidine equilibrates with (2CaO · SiO 2 ) 2 CaF 2 , CaO · SiO 2 , 3CaO · 2SiO 2 , 2CaO · SiO 2 and CaF 2 in solid state. Cuspidine coexists with liquid phases at temperatures between 1 387 K and 1 680 K.

show abstract

Section: Introductionmentioning

confidence: 99%

Stability of Cuspidine (3CaO 2SiO2 CaF2) and Phase Relations in the CaO-SiO2-CaF2 System.

2002

View full text Add to dashboard Cite

show abstract

“…Horizontal heat transfer and lubrication performance of slag are strongly dependent on the crystallization characteristics of the slag. [1][2][3][4][5][6] Therefore, it is required that ESR type slags possess proper crystallization properties to meet the requirements for heat transfer control and lubrication performance in drawing-ingot-type ESR process.…”

Section: Introductionmentioning

confidence: 99%

“…[8][9][10][11][12][13][14][15] The conventional such mold fluxes contain 70 mass pct (CaO+SiO 2 ), 2 to 6 mass pct Al 2 O 3 , 2 to 10 mass pct Na 2 O(+K 2 O), 0 to 10 mass pct F with varying addition of MgO, TiO 2 , B 2 O 3 , Li 2 O, etc., and basicity (mass pct CaO/mass pct SiO 2 ) of the fluxes ranges from 0.7 to 1.3. [4] In view of the significant difference in the slag chemistry, the crystallization behaviors of ESR type CaF 2 -CaO-Al 2 O 3 -(SiO 2 ) slags should be different from those of the mold fluxes.…”

Section: Introductionmentioning

confidence: 99%

Effect of SiO2 on the Crystallization Behaviors and In-Mold Performance of CaF2-CaO-Al2O3 Slags for Drawing-Ingot-Type Electroslag Remelting

Shi

Cho

et al. 2015

Metall Mater Trans B

View full text Add to dashboard Cite

The crystallization characteristics of CaF 2 -CaO-Al 2 O 3 slags with varying amounts of SiO 2 were experimentally studied. The effects of slag crystallization behaviors on the horizontal heat transfer and lubrication performance in drawing-ingot-type electroslag remelting (ESR) were also evaluated in terms of as-cast ingots surface quality and drawing-ingot operation. The results show that increasing SiO 2 addition from 0 to 6.8 mass pct strongly suppresses the crystallization of ESR type CaF 2 -CaO-Al 2 O 3 slags. The crystallization temperature of the studied slags decreases with the increase in SiO 2 addition. The liquidus temperatures of the slags also show a decreasing trend with increasing SiO 2 content. In CaF 2 -CaO-Al 2 O 3 -(SiO 2 ) slags, faceted 11CaOAE7Al 2 O 3 AECaF 2 crystals precipitate first during continuous cooling of the slag melts, followed by the formation of CaF 2 at lower temperatures. 11CaOAE7Al 2 O 3 AECaF 2 was confirmed to be the dominant crystalline phase in the studied slags. CaF 2 -CaO-Al 2 O 3 slags with a small amount of SiO 2 addition are favorable for providing sound lubrication and horizontal heat transfer in mold for drawing-ingot-type ESR, which consequently bring the improvement in the surface quality of ESR ingot and drawing-ingot operating practice as demonstrated by plant trials.

show abstract

“…This requires that the heating source, simulating the strand, has sufficient power to balance the heat extracted by a water-or air-cooled body simulating the mold and that steady-state conditions are established. Heating methods involved direct resistance heating, [14] electrical resistance cartridges, [15] electromagnetic induction heating, [16,17] and gas burners. [7] These kinds of methods were used with slag film thicknesses between 0.5 and 3.0 mm and showed that the heat flux can vary considerably with slag composition.…”

Section: Introductionmentioning

confidence: 99%

“…For studying heat transfer, different methods were devised and, according to their experimental principles, were classified into three categories: (1) sandwiching a mold slag layer between hot and cold solid walls, [7,[14][15][16][17] (2) dipping a cold finger into molten slag [8,9,18,19] or into a bath of molten slag and steel, [20,21] and (3) exposing a mold slag layer to infrared radiation. [22][23][24][25] In the sandwiching methods, measures are taken to establish linear temperature gradients through the measuring system, which consists of hot body, mold flux film, and cold body.…”

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

View full text Add to dashboard Cite

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.

show abstract

Thermal Resistance at the Interface between Mold Flux Film and Mold for Continuous Casting of Steels.

Cited by 138 publications

References 1 publication

Stability of Cuspidine (3CaO 2SiO2 CaF2) and Phase Relations in the CaO-SiO2-CaF2 System.

Stability of Cuspidine (3CaO 2SiO2 CaF2) and Phase Relations in the CaO-SiO2-CaF2 System.

Effect of SiO2 on the Crystallization Behaviors and In-Mold Performance of CaF2-CaO-Al2O3 Slags for Drawing-Ingot-Type Electroslag Remelting

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

Contact Info

Product

Resources

About