Please use this identifier to cite or link to this item: http://buratest.brunel.ac.uk/handle/2438/8341
Title: Macrosegregation in direct-chill casting of aluminium alloys
Authors: Nadella, R
Eskin, DG
Du, Q
Katgerman, L
Keywords: Aluminium alloys;Direct-chill casting;Macrosegregation;Grain refining
Issue Date: 2008
Publisher: Elsevier
Citation: Progress in Materials Science, 53(3), 421 - 480, 2008
Abstract: Semi-continuous direct-chill (DC) casting holds a prominent position in commercial aluminium alloy processing, especially in production of large sized ingots. Macrosegregation, which is the non-uniform chemical composition over the length scale of a casting, is one of the major defects that occur during this process. The fact that macrosegregation is essentially unaffected by subsequent heat treatment (hence constitutes an irreversible defect) leaves us with little choice but to control it during the casting stage. Despite over a century of research in the phenomenon of macrosegregation in castings and good understanding of underlying mechanisms, the contributions of these mechanisms in the overall macrosegregation picture; and interplay between these mechanisms and the structure formation during solidification are still unclear. This review attempts to fill this gap based on the published data and own results. The following features make this review unique: results of computer simulations are used in order to separate the effects of different macrosegregation mechanisms. The issue of grain refining is specifically discussed in relation to macrosegregation. This report is structured as follows. Macrosegregation as a phenomenon is defined in the Introduction. In “Direct-chill casting – process parameters, solidification and structure patterns” section, direct-chill casting, the role of process parameters and the evolution of structural features in the as-cast billets are described. In “Macrosegregation in direct-chill casting of aluminium alloys” section, macrosegregation mechanisms are elucidated in a historical perspective and the correlation with DC casting process parameters and structural features are made. The issue of how to control macrosegregation in direct-chill casting is also dealt with in the same section. In “Role of grain refining” section, the effect of grain refining on macrosegregation is introduced, the current understanding is described and the contentious issues are outlined. The review is finished with conclusion remarks and outline for the future research.
Description: This is the post-print version of the final paper published in Progress in Materials Science. 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.
URI: http://www.sciencedirect.com/science/article/pii/S007964250700059X
http://bura.brunel.ac.uk/handle/2438/8341
DOI: http://dx.doi.org/10.1016/j.pmatsci.2007.10.001
ISSN: 0079-6425
Appears in Collections:Publications
Brunel Centre for Advanced Solidification Technology (BCAST)

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