Effect of inlet geometry on macrosegregation during the direct chill casting of 7050 alloy billets: experiments and computer modelling

Zhang, L; Eskin, Dmitry; Miroux, A.; Subroto, Tungky; Katgerman, L.

doi:10.1088/1757-899x/33/1/012019

Cited by 12 publications

(8 citation statements)

References 14 publications

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“…8a with real Cu segregation in the semi-horizontal feeding scheme (Fig. 5a), a good agreement can be found [16]. It should be noted that the segregation curve in Fig.…”

Section: Control Of Macrosegregation By a Melt Distribution Systemsupporting

confidence: 73%

Mechanisms and Control of Macrosegregation in Dc Casting

Eskin

2014

Light Metals 2014

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Macrosegregation is a severe, unrecoverable defect often occurring in large-scale castings. This paper offers a critical review of mechanisms involved in the formation of macrosegregation during DC casting of aluminum alloys. These mechanisms include thermo-solutal and forced convection, shrinkage-driven flow and transport of solid crystals. It is demonstrated that the impact of melt flow on macrosegregation depends on the flow direction and pattern, and on the extent of the slurry zone in the sump. The shrinkage-induced flow contributes to the negative centerline segregation but this contribution depends on the shape of the macroscopic solidification front and on the permeability of the mushy zone. Accumulation of floating crystals will result in negative segregation but the occurrence of these grains and their composition depends on grain refinement and melt flow pattern. It is shown that macrosegregation can be controlled by practical means such as process parameters, structure modification and melt flow management.

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“…8a with real Cu segregation in the semi-horizontal feeding scheme (Fig. 5a), a good agreement can be found [16]. It should be noted that the segregation curve in Fig.…”

Section: Control Of Macrosegregation By a Melt Distribution Systemsupporting

confidence: 73%

Mechanisms and Control of Macrosegregation in Dc Casting

Eskin

2014

Light Metals 2014

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“…Reddy and Beckermann [9] made the first attempts to account for the impact of grain motion on macrosegregation formation assuming spherical grains. In DC casting, both globular and dendritic grain morphologies can be observed [10,11] . Simplifications of the dendritic morphology by considering globular grains in numerical models resulted in large discrepancies between model predictions and experiments [12] .…”

Section: Bintroductionmentioning

confidence: 99%

A Simplified Three-Phase Model of Equiaxed Solidification for the Prediction of Microstructure and Macrosegregation in Castings

Tveito

Pakanati

M’Hamdi

et al. 2018

Metall Mater Trans A

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Macrosegregation is a result of the interplay of various transport mechanisms, including natural convection, solidification shrinkage, and grain motion. Experimental observations also indicate the impact of grain morphology, ranging from dendritic to globular, on macrosegregation formation. To avoid the complexity arising due to modelling of an equiaxed dendritic grain, we present the development of a simplified three-phase, multiscale equiaxed dendritic solidification model based on the volume averaging method, that accounts for the above-mentioned transport phenomena. The validity of the model is assessed by comparing it to the full three phase model without simplifications. It is then applied to qualitatively analyze the impact of grain morphology on macrosegregation formation in an industrial scale direct chill (DC) cast aluminium alloy ingot.

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“…Zhang et al [3,4] conducted a series of DC cast billet experiments of AA7050 to study the impact of inlet melt flow on macrosegregation and microstructure formation. Of the two kinds of inlet melt flow, one involved a vertical jet.…”

Section: Bintroductionmentioning

confidence: 99%

“…By using inlet jet, complete resuspension of the equiaxed grains away from the center of the billet was observed. Inspite of this, Zhang et al [3] observed severe solute depletion at the center of the billet due to washing away of the solute by the strong inlet vertical jet. Wagstaff and Allanore [2] conducted experiments on an ingot with Al -4.5% Cu binary alloy.…”

Section: Bintroductionmentioning

confidence: 99%

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Impact of Inlet Flow on Macrosegregation Formation Accounting for Grain Motion and Morphology Evolution in DC Casting of Aluminium

Pakanati

Tveito

M’Hamdi

et al. 2018

The Minerals, Metals &Amp; Materials Series

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Several transport mechanisms contribute to macrosegregation formation in Direct Chill (DC) casting of aluminium. The latter include solidification shrinkage induced flow, thermal-solutal convection and grain motion. The relative importance of these transport mechanisms depends on process parameters such as cast velocity, inlet melt flow, cooling rate, cast dimensions etc. Of these, the inlet melt flow due to vertical jet is known to cause significant modification in macrosegregation by resuspending equiaxed grains at the center of the ingot/billet. In this paper, we investigate by means of modeling the macrosegregation formation due to an inlet vertical jet. For this purpose, a threephase, multiscale solidification model accounting for above mentioned transport phenomena except for shrinkage induced flow is applied on a DC cast billet. The model considers grain motion accounting for both globular and dendritic equiaxed grain growth and we investigate their interaction with the inlet vertical jet. We show that an interplay of morphology evolution of equiaxed grains and inlet vertical jet together contribute to grain resuspension which in turn modifies macrosegregation formation. We also compare these results with a case with open inlet.

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Effect of inlet geometry on macrosegregation during the direct chill casting of 7050 alloy billets: experiments and computer modelling

Cited by 12 publications

References 14 publications

Mechanisms and Control of Macrosegregation in Dc Casting

Mechanisms and Control of Macrosegregation in Dc Casting

A Simplified Three-Phase Model of Equiaxed Solidification for the Prediction of Microstructure and Macrosegregation in Castings

Impact of Inlet Flow on Macrosegregation Formation Accounting for Grain Motion and Morphology Evolution in DC Casting of Aluminium

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