Roll-strip Interfacial Heat Fluxes in Twin-roll Casting of Low-carbon Steels and Their Effects on Strip Microstructure.

Tavares, Roberto Parreiras; Isac, Mihaiela; Guthrie, R. I. L.

doi:10.2355/isijinternational.38.1353

Cited by 26 publications

(21 citation statements)

References 2 publications

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“…This reagent is capable of showing the degree of micro-segregation, and in this context, it is able to distinguish the iron-rich dendritic region (as the black region) and the impurity-rich inter-dendritic spaces (as the white region). 44) As shown in the figure, the slower cast, thicker strip, exhibits a columnar dendritic structure, with the dendrites meeting in the centerline of the strip and the absence of an equiaxed region. However, as marked by the arrows, various broken and bent dendrites were observed, showing signs of interaction between columnar dendrites growing from the two sides.…”

Section: Mathematical and Physical Modeling Of Strip Casing Processesmentioning

confidence: 86%

“…As such, these fluxes need to be carefully controlled. Work performed by Tavares, Isac and Guthrie had shown that casting conditions of a TRC process has a significant influence on the solidification and as-cast microstructure of the strip, 44) as shown in Fig. 15.…”

Section: Mathematical and Physical Modeling Of Strip Casing Processesmentioning

confidence: 99%

“…This usually occurs due to relatively large inter-dendritic spaces commonly associated with low cooling rates, which was exactly the case for the slower casting speed. 44) The second micrograph in Fig. 15 was obtained from a thinner as-cast strip at higher casting speed.…”

Section: Mathematical and Physical Modeling Of Strip Casing Processesmentioning

confidence: 99%

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Progress in Strip Casting Technologies for Steel; Technical Developments

2013

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The present article is a sequel to the previous review on the history of near net shape strip casting facilities. The present review focuses on technical progress made in strip casting over the last three decades. Strip casting is a revolutionary technology that promises the hope for an efficient, economical and environmentally-friendly process to produce hot-rolled, steel sheets. This review provides a summary of the theory, recent research, and progress, in the developments of strip casting operations for steels, along with technical discussions regarding the characteristics and design features of steel strip casting machines. Two strip casting processes are discussed in detail; the Twin-Roll Casting (TRC) process and the Horizontal Single-Belt Casting (HSBC) process. Particular emphasis is placed on topics such as the commercial potential for strip casting technology in the steel industry, and the economic and environmental advantages of direct strip production, versus current continuous casting, fixed mold technologies.

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Section: Mathematical and Physical Modeling Of Strip Casing Processesmentioning

confidence: 86%

Section: Mathematical and Physical Modeling Of Strip Casing Processesmentioning

confidence: 99%

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Progress in Strip Casting Technologies for Steel; Technical Developments

2013

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“…It shows the predicted fluid flow field generated in a 0.6m roll diameter pilot caster in Canada, using a conventional submerged entry nozzle of the bifurcated type used for slab casters. 30,31) The corresponding solidification profiles 32) are shown in Fig. 20(b), where it is seen that the centre of the forming shell is thicker halfway down the sump, than at the sides.…”

Section: Moving Mould Technologies For Strip and Thin Slabmentioning

confidence: 99%

A Review of Fluid Flows in Liquid Metal Processing and Casting Operations

Guthrie

2009

ISIJ Int.

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Fluid flows have proved to be an integral part of many metallurgical processing operations. Metal, slag, and gas flows invariably affect the viability, effectiveness, and efficiency, of our reactor vessels. The performance characteristics of our blast furnaces and steelmaking vessels, such as BOF's, OBM's, ladles, tundishes, and the moulds of continuous casting machines, are all strongly influenced by such flows. Similarly, liquid metal quality and cast micro-structures, are also bound up with the way fluids have flowed and interacted. In all these aspects, the rapid evolution in our techniques and abilities to mathematically and physically model single and multi-phase flows and their attendant heat and mass transfer processes, have contributed significantly to our understanding, and ability, to control and improve these metallurgical processing operations, and to develop new and better processes. The evolution and application of computational fluid dynamics (CFD) over the past four decades has been particularly impressive. The author's many fine Japanese graduate students have made very valuable contributions to this new field of research for Process Metallurgists, as well as to the founding and scientific support of the McGill Metals Processing Centre, MMPC, following their return to Japan.KEY WORDS: fluid flow; computational fluid dynamics; water models; blast furnace; steelmaking vessels; ladles; tundishes; moulds; continuous casting; strip casting; horizontal single belt casting; inclusions; liquid metal quality; LiMCA; ESZ-pas; ab-initio heat flux predictions. 1453© 2009 ISIJ Review gical and hydro-metallurgical, all involve fluid flows, in one way or another, in association with heat and mass exchanges between gaseous, liquid and solid phases.Today, fluid flows still abound for the material scientists, but I suspect few appreciate it, unless their educational background includes a little Process Metallurgy, or its equivalent. Consider the production of advanced materials involving the chemical vapor deposition (CVD) of turbine blade super-alloys with nickel based deposits of alumina, or the transport of SiF 4 gas and special additives onto the insides of glass tubes so as to create fibre-optic cables, or the wetting and coating of plastic compact discs with molten aluminum, or the role of natural convection in the production of single crystals of silicon from a melt, etc., etc. The Theory of Fluid FlowsWhat exactly do we know about fluid mechanics? Stripped to its essence, a fluid is defined as a substance that cannot sustain shear stresses without moving. For instance, a stable, motionless pool of liquid steel can be contained within an adiabatic ladle, but if there are any heat losses to the walls, thermal density differences between cooler steel at the sidewalls will lead to gradients in density and therefore weight. These spatial differences in gravitational forces, in turn, will generate re-circulatory natural convective flows. Similarly, once a tap-hole or slide-gate nozzle is opened, the large stat...

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“…34) During further solidification, the roll surface separated from melt by the solidified shell. At this stage of solidification, the shell may lift off from the roll surface 35,36) due to depression and distortion as shown in Fig. 2, which are attributed to thermal stresses exceeding the yield point of the material.…”

Section: Influence Of Melt On Roll Surfacementioning

confidence: 99%

Wear of Roll Surface in Twin-roll Casting of 4.5% Si Steel Strip.

Zapuskalov

Vereschagin

2000

ISIJ International

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The rolls are one of the most important components of the twin-roll casting process, determining not only strip quality, but due to their expense, add to the price of the as-cast strip. The potential for reducing operational cost and ensuring required strip quality may be achieved through a reduction in wear of the roll surface and hence reduced frequency of roll surface reconditioning and replacement. To achieve this, it is imperative to understand the mechanisms of roll surface wear which occur during casting operations.The present study was aimed at determining the influence of liquid metal, roll separation force and strip incline from the vertical casting direction on the wear of the roll surface in a twin-roll casting process.It was found that roll wear in the twin-roll casting process is accompanied by removal of material from the roll surface and redistribution of topography of the roll surface. Applying high roll separation forces lead to increase erosion of the roll surface and coarsening of the roll surface topography. Roll surface wear caused by deformation occurs by imprinting of the strip surface on the roll surface as well as grinding of the roll surface by the strip. Even with the application of high roll separation forces the highest contribution to wear of the roll surface is by the interaction of the melt with the roll surface in the very early stages of solidification.KEY WORDS: rapid solidification process; twin-roll process; strip casting; wear; surface roughness.surface. To achieve this, it is imperative to understand the mechanism of roll surface wear which occurs during casting operations. It is of particular interest to relate the influence of liquid metal attack, roll separation force and effect of strip incline to the roll surface wear.The term wear remains a subject of some debate, 22) so to avoid confusion in this discussion the term wear in this work is accepted as "damage to a solid surface, generally involving progressive loss of material, due to relative motion between that surface and a contacting substance or substances". 23) Experimental Equipment and Procedure Twin-roll Casting ProcessAn experimental investigation was carried out on a twin roll caster 24,25) schematically showed in Fig. 1. Steel melt was prepared from 50 kg ingots which were melted under an argon atmosphere in an induction furnace, yielding the following composition: 4.5% Si, 0.0013% Cu, CϽ0.007%, PϽ0.010%, NiϽ0.07%, TiϽ0.02%, CoϽ0.02% and AlϽ0.01%.The superheat was maintained at ϳ30°C and the melt entered the gap between the rolls through a slot in a ceramic nozzle. The cylindrical, water-cooled rolls constructed from Cu-Cr sleeves were ϳ440 mm in diameter and 150 mm in length. The casting speed was 7 m s Ϫ1 and the thickness of the as-cast strip 0.1-0.2 mm.The roll surface before casting was treated with an emery wheel. The roll surface obtained in this manner was further treated with fine emery paper to obtain a roughness of the roll surface, R a ϭ0.4 mm.The roll separation force per unit length of the ro...

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Roll-strip Interfacial Heat Fluxes in Twin-roll Casting of Low-carbon Steels and Their Effects on Strip Microstructure.

Cited by 26 publications

References 2 publications

Progress in Strip Casting Technologies for Steel; Technical Developments

Progress in Strip Casting Technologies for Steel; Technical Developments

A Review of Fluid Flows in Liquid Metal Processing and Casting Operations

Wear of Roll Surface in Twin-roll Casting of 4.5% Si Steel Strip.

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