Formation des microstructures et des microségrégations intragranulaires en solidification initiale des aciers au cuivre

Abstract : This study deals with the formation of microstructures and microsegregatlons during solidification of the first hundreds of [micro]m by continuous casting of copper-rich steels. Two kinds of experiments were performed to reproduce at the laboratory scale thermal conditions comparable to shell solidification by continuous casting : - laser remelting experiments, - droplets fall experiments using a copper-substrate instrumented with a Si-photodiode. Measurements performed with the photodiode were used to estimate the evolution of the thermal conditions (thermal gradient and solidification rate) during the solidification of the first 500 µm in the droplets. The whole of experiments shows that two different kinds of microstructures can form in the chilI zone of copper-rich steels : cells and dendrites. Copper microsegregations were measured in laser remelted samples and in droplets solidified on the substrate instrumented with the Si-photodiode. Additional experiments were performed with a Bridgman furnace to make easier the interpretation of the results. These experiments bring out the important roIe of copper diffusion in residiual liquid of the mushy zone in case of cellular growth. Solute diffusion in the liquid results in an important undercooling at the cell tip and contributes to reduce significantly the amplitude of microsegregations formed during initial solidification.
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Theses
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http://docnum.univ-lorraine.fr/prive/INPL_T_2001_LADEUILLE_L.pdf
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https://hal.univ-lorraine.fr/tel-01750322
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Submitted on : Thursday, March 29, 2018 - 12:42:56 PM
Last modification on : Monday, April 16, 2018 - 10:41:05 AM

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  • HAL Id : tel-01750322, version 1

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Laurent Ladeuille. Formation des microstructures et des microségrégations intragranulaires en solidification initiale des aciers au cuivre. Autre [cond-mat.other]. Institut National Polytechnique de Lorraine, 2001. Français. ⟨NNT : 2001INPL052N⟩. ⟨tel-01750322⟩

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