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Modélisation numérique multi-échelle des structures de solidification, de la macroségrégation et de la Transition Colonnaire-Equiaxe

Abstract : As part of the french SOFT-DEFIS project, this work aims to contribute to the development of a numerical tool predicting the formation of equiaxed and columnar solidification structures, as well as the transition zone and associated chemical segregations during large steel ingots casting. Until now, models generally use the finite volume method. A first model based on the finite element method has been proposed but limited to equiaxed solidification. The latter is extended to model both columnar and equiaxed structures. A Level-Set method is applied in order to follow the growth of the columnar front. Its velocity is calculated using a growth kinetics model developed for dendritic microstructures. Equiaxed grains develop in the undercooled liquid ahead of the columnar front and can be transported. Two sources of equiaxed grains are modeled : heterogeneous germination as well as fragmentation. The model considers the dendritic morphology for the two microstructures. A solutal blocking criterion is used to predict the position of the columnar-to-equiaxed transition.The conservation equations are solved using a splitting method separating the two stages of transport and growth. 2D and 3D simulations of small ingots serve as test for the different parts of the model. Finally, the model is applied at thescale of industrial ingots to predict the evolution of developed structures and segregated zones, in comparison with the experimental analyzes of the project partners.
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Submitted on : Thursday, November 18, 2021 - 3:47:59 PM
Last modification on : Saturday, November 20, 2021 - 3:05:46 AM

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  • HAL Id : tel-03435152, version 1

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Hanadi Ettroudi. Modélisation numérique multi-échelle des structures de solidification, de la macroségrégation et de la Transition Colonnaire-Equiaxe. Mécanique des matériaux [physics.class-ph]. Université Paris sciences et lettres, 2021. Français. ⟨NNT : 2021UPSLM021⟩. ⟨tel-03435152⟩

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