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Essais de coulabilité en fonderie : Aspects thermiques, hydrodynamiques et structures de solidification

Abstract : The flowability test is commonly practiced for casting thin pieces. The liquid metal is injected into a tubular mold and the length traveled by the metal before solidification stops measure the flowability. From the theoretical point of view, solidification of thin pieces involves coupled phenomena as hydrodynamic during the filling lasts a few tenths of a second, the heat transfer, especially the metal mold exchanges and solidification mechanisms. The flow is modified by solidification. Conversely, the grain structure is sensitive to flow. The field of temperature is highly dependent on the flow, mainly in the vicinity of gas-liquid front. We proposed an analytical formulation of the current lines. Then we realized several series of tests on cast iron and alloy Al-2% Cu. These tests showed that the metal-mold heat transfer can be represented by a transfer coefficient, which depends on the injection velocity. The tests on cast iron allowed to follow continuously the progress of the liquid while recording the temperature of the liquid front. Testing the aluminum alloy include measures on the columnar-equiaxed transition and on the grain size. We have established a model of nucleation and growth of equiaxed that calculates the size of grains from the cooling conditions. Various measures, processed by simplified models, allow us to propose a “gel stopping mechanism in crust” : liquid flow, formation of columnar crust, its closure equiaxed crystallization band, crystallization stopping the columnar growth. These results and the corresponding models will be used to validate a numerical code under development in the framework of the European program "Convective effects in solidification”.
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Submitted on : Friday, July 1, 2016 - 11:32:44 AM
Last modification on : Tuesday, December 7, 2021 - 2:08:08 PM

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  • HAL Id : tel-01340526, version 1

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Brahim Garda. Essais de coulabilité en fonderie : Aspects thermiques, hydrodynamiques et structures de solidification. Electromagnétisme. INSTITUT NATIONAL POLYTECHNIQUE DE GRENOBLE, 1993. Français. ⟨tel-01340526⟩

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