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Title: Effect of different grain structures on centerline macrosegregation during direct-chill casting
Authors: Eskin, DG
Nadella, R
Katgerman, L
Keywords: Macrosegregation;Microsegregation;Aluminum alloy;Direct-chill casting;Floating grains
Issue Date: 2008
Publisher: Elsevier
Citation: Acta Materialia, 56(6), 1358 - 1365, 2008
Abstract: Duplex grain structure consisting of coarse-cell and fine-cell dendritic grains is frequently found in the central portion of direct-chill cast billets and ingots. Coarse-cell grains are usually considered as free-floating crystals settled to the bottom of the billet sump. These grains are assumed to be solute-lean and contribute to the negative centerline segregation. In this paper the contribution of coarse-cell and fine-cell grains to macrosegregation is for the first time studied experimentally by direct measurements of their composition. It is shown that the coarse-cell, floating grains are depleted of solute and the areas of their accumulation contribute to the negative macrosegregation. The areas of fine-cell grains can be either enriched in solute or be close to the nominal composition. It is argued that their composition results from the interplay between thermo-solutal and shrinkage-induced flows. The roles of casting speed and grain refining are also under scrutiny in this paper.
Description: This is the post-print version of the final paper published in Acta Materialia. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2008 Elsevier B.V.
ISSN: 1359-6454
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Brunel Centre for Advanced Solidification Technology (BCAST)

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