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Article Dans Une Revue Metallurgical and Materials Transactions A Année : 2017

Modeling of the Coupling of Microstructure and Macrosegregation in a Direct Chill Cast Al-Cu Billet

Résumé

The macroscopic multiphase flow and the growth of the solidification microstructures in the mushy zone of a direct chill (DC) casting are closely coupled. These couplings are the key to the understanding of the formation of the macrosegregation and of the nonuniform microstructure of the casting. In the present paper we use a multiphase and multiscale model to provide a fully coupled picture of the links between macrosegregation and microstructure in a DC cast billet. The model describes nucleation from inoculant particles and growth of dendritic and globular equiaxed crystal grains, fully coupled with macroscopic transport phenomena: fluid flow induced by natural convection and solidification shrinkage, heat, mass, and solute mass transport, motion of free-floating equiaxed grains and of grain-refiner particles. We compare our simulations to experiments on grain-refined and non grain-refined industrial size billets from literature. We show that a transition between dendritic and globular grain morphology triggered by the grain refinement is the key to the explanation of the differences between the macrosegregation patterns in the two billets. We further show that the grain size and morphology are strongly affected by the macroscopic transport of free-floating equiaxed grains and of grain-refiner particles.

Domaines

Matériaux
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Dates et versions

hal-01709089 , version 1 (14-02-2018)

Identifiants

Citer

Laurent Heyvaert, Marie Bedel, Miha Založnik, Hervé Combeau. Modeling of the Coupling of Microstructure and Macrosegregation in a Direct Chill Cast Al-Cu Billet. Metallurgical and Materials Transactions A, 2017, 48 (10), pp.4713-4734. ⟨10.1007/s11661-017-4238-z⟩. ⟨hal-01709089⟩
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