Effect of different grain structures on centerline macrosegregation during direct-chill casting

被引：81

作者：

Eskin, D. G. ^{[1
]}

Nadella, R. ^{[1
]}

Katgerman, L. ^{[2
]}

机构：

[1] Netherlands Inst Met Res, NL-2628 CD Delft, Netherlands

[2] Delft Univ Technol, Dept Mat Sci & Engn, NL-2628 CD Delft, Netherlands

来源：

ACTA MATERIALIA | 2008年 / 56卷 / 06期

关键词：

macrosegregation; microsegregation; aluminum alloy; direct-chill casting; floating grains;

D O I：

10.1016/j.actamat.2007.11.021

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

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 macro segregation 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. (C) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

引用

页码：1358 / 1365

页数：8

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