Growth of Solidified Shell Just below the Meniscus in Continuous Casting Mold

Hanao, Masahito; Kawamoto, Masayuki; Yamanaka, Akihiro

doi:10.2355/isijinternational.49.365

Cited by 48 publications

(38 citation statements)

References 21 publications

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“…In this experimental procedures, the liquid steel directly touches with the chill copper mold, therefore, it is expected that the initial heat flux should reach about 10MW/m 2 [11], which is higher than a few MW/m 2 in ordinary C.C. processes [12]. However, such a high initial heat flux immediately decreases in a second to the level of ordinary C.C.…”

Section: Methodsmentioning

confidence: 99%

“…From this measurement, the minimum solidification velocity was estimated to be about 0.5mm·s -1 . As for the maximum solidification velocity near the copper mold, we refer to about 3mm·s -1 , which was estimated in continuously cast slab by the analysis of heat flow [12], because the cooling condition and the as-cast structures in our experimental equipment are quite similar to those in the continuous casting [13]. In our experiment, the initial heat flux should be higher than that in ordinary C.C.…”

Section: Numerical Analysis For the Transition Of Primary Crystalmentioning

confidence: 99%

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Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

2012

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Formation processes of as-cast γ grain structures during casting of hyperperitectic carbon steels with 0.15-0.45 mass% carbon concentrations have been studied by means of a rapid unidirectional solidification technique. In steels with 0.15-0.41 mass% carbon concentrations, coarse columnar γ grains (CCG) with a minor axis diameter of 1-3mm developed along the direction of temperature gradient. In a steel with 0.38 mass% carbon, importantly, columnar γ grains (CG) whose minor axis diameter is less than 500 μm form before the formation of CCG and the grain structure discontinuously changes from CG to CCG. The fraction of CG region increases with increase in the carbon concentration. In the samples with the carbon concentration higher than 0.43 mass%, the as-cast structure consists of CG over almost the entire ingots. Analyses on a relation between γ grain and dendrite structures and their crystallographic orientations indicate that the formation of CG originates from the primary solidification of γ phase instead of δ phase. This is supported by numerical analysis on the dendrite growths.

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Section: Methodsmentioning

confidence: 99%

Section: Numerical Analysis For the Transition Of Primary Crystalmentioning

confidence: 99%

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

2012

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“…From many previous investigations showed that there exists a peak (maximum) mold heat transfer rate at certain point of casting mold. For example, Hanao et al 12) reported that 45 mm below meniscus is the position of peak heat transfer rate while Meng et al 13) suggested 55 mm below the meniscus. The heat transfer in the casting mold can be regarded as 1-dimensional below the position of peak heat transfer rate, as schematically shown in Fig.…”

Section: Evaluations Of Mold Fluxes Testedmentioning

confidence: 99%

Assessment of CaO^|^ndash;Al2O3 Based Mold Flux System for High Aluminum TRIP Casting

Cho

Blazek

Frazee³

et al. 2013

ISIJ Int.

143

116

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Today, the demands for Advanced High Strength Steels (AHSS) have gradually increased due to their ability to reduce vehicle weight as a means to save energy, reduce the environmental impact while simultaneously improving passenger safety. However, AHSS often require the addition of large amounts of alloying elements such as aluminum and this can make it difficult to cast sound slabs without surface defects. When casting high aluminum AHSS, due to the reaction between aluminum in steel and silica in mold flux, the viscosity and crystallization characteristics of the mold slag changes drastically, and deteriorates mold lubrication. Therefore, it is critical to limit the reaction between Al in steel and mold slag and at the same time to provide consistent and adequate mold slag in-use properties. This paper describes the development of non-traditional lime-alumina based mold fluxes which have the potential to reduce slag-steel interaction during casting of high aluminum TRIP steel. Several trial casts of 1.45% Al TRIP steel have been conducted on a pilot caster to examine the performance of mold fluxes developed. When the lime-alumina based mold fluxes were applied successfully, alumina pickup was reduced to less than 5% as compared to 15% alumina pickup for corollary trial casts using conventional lime-silica mold fluxes. The developed lime-alumna mold fluxes showed improved in-mold performance as indicated by enhanced lubrication and stable mold heat transfer, again compared to lime-silica fluxes. Cast slabs from the trials using these lime-alumina fluxes have periodic and sound oscillation marks and minimized defects.

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“…Contrary to the generalized perception, slag infiltration fluctuates not only in the casting direction but also along the mould width. A clear example of this behaviour is the use of inverted port SEN's to promote heat delivery to the meniscus and ensure lubrication in the mould corners 82,83) (Fig. 12).…”

Section: Effect Of Flow Dynamics Heat Transfer and Solidificationmentioning

confidence: 99%

Key Lubrication Concepts to Understand the Role of Flow, Heat Transfer and Solidification for Modelling Defect Formation during Continuous Casting

López¹,

Jalali

Sjöström³

et al. 2018

ISIJ Int.

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Surface defects are recurrent problems during Continuous Casting of steel due to the introduction of new grades that are often difficult to cast, as well as the everlasting pursuit for higher quality and improved yield. Accordingly, numerical modelling has become a ubiquitous tool to analyse the formation mechanisms of such defects. However, industrial application of simulations is often hampered by oversimplifications and omissions of important process details such as variations in material properties, specific casting practices or shortcomings regarding fundamental metallurgical concepts. The present manuscript seeks to create awareness on these issues by visiting key notions such as slag infiltration, interfacial resistance and Lubrication Index. This is done from a conceptual point of view based on industrial observations and numerical modelling experiences. The latter allows a re-formulation of outdated concepts and misconceptions regarding the influence of fluid flow, heat transfer and solidification on lubrication and defect formation. Additionally, the manuscript addresses common challenges and constraints that occur during industrial implementation of numerical models such as the lack of high-temperature material data for slags. Finally, the manuscript provides examples of improvements on product quality and process stability that can be achieved through a holistic approach which combines modelling with laboratory tests, experiences from operators and direct plant measurements.KEY WORDS: numerical modelling; Continuous Casting; defects; lubrication; powder consumption.introduced as an alternative to study such issues in a more cost-efficient way than using traditional trial-error tests in the plant. Starting in the late 70's and 80's with the advent of personal computers, the first generation of models managed to predict the overall behaviour of the caster based on empirical data. 5-7) Subsequently, models in the 90's added Computational Fluid Dynamics (CFD) and solidification to casting simulations. [8][9][10] Faster computers and improved codes allowed huge progress regarding multi-phase applications (e.g. bubbles and inclusions) combined with calculations of flow and solidification in the past decade. 11-14)Currently, a wide variety of commercial and in-house codes are available for CC modelling such as PROCAST, COMSOL, TEMPSIMU, CON1D/2D, etc. [15][16][17] Moreover, a recent trend is the development of thermo-mechanical models coupled to flow dynamics for solving the combined problem of flow, solidification and stress-strain during casting. 18,19) Of all these, PHYSICA and THERCAST are two of the most promising approaches; which allow: a) 3D unstructured -mesh, multi-physics model using a combina-

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Growth of Solidified Shell Just below the Meniscus in Continuous Casting Mold

Cited by 48 publications

References 21 publications

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

Transition of solidification mode and the as-cast γ grain structure in hyperperitectic carbon steels

Assessment of CaO^|^ndash;Al2O3 Based Mold Flux System for High Aluminum TRIP Casting

Key Lubrication Concepts to Understand the Role of Flow, Heat Transfer and Solidification for Modelling Defect Formation during Continuous Casting

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