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Theses

Refusion sous vide d’alliages de titane : comportement de l’arc électrique et conditions aux limites

Abstract : In the vacuum arc remelting process, the structure and dynamics of the electric arc are responsible for the spatial distributions of energy and current at the top of the remelted ingot. Those distributions strongly impact the ingot temperature field and the liquid metal velocity field, which govern the ingot solidification conditions, hence the final product quality. A study based on the optical measurement of the electric arc dynamics at a long time-scale during vacuum arc remelting of titanium alloys was undertaken. This analysis was performed either qualitatively using melt video recordings, or quantitatively by a new specifically developed diagnostic technique based on the use of photodiodes. The analysis of the electric arc dynamics confirmed the presence of an ensemble arc motion during vacuum arc remelting of titanium alloys and showed a strong correlation between the observed dynamics and the magnitude of the imposed electromagnetic stirring. Furthermore, our results allow to predict the arc dynamics in non-studied conditions and to propose possible origins for the observed behaviors. Finally, a first simulation of the influence of the arc behavior is proposed in order to study its impact on the ingot solidification. This work comprises also a detailed modelling of the thermal radiation at the ingot top, based on the radiosity method
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https://tel.archives-ouvertes.fr/tel-01877392
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Submitted on : Wednesday, September 19, 2018 - 4:50:05 PM
Last modification on : Monday, April 6, 2020 - 2:44:04 PM

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DDOC_T_2018_0020_DELZANT.pdf
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  • HAL Id : tel-01877392, version 1

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Pierre-Olivier Delzant. Refusion sous vide d’alliages de titane : comportement de l’arc électrique et conditions aux limites. Matériaux. Université de Lorraine, 2018. Français. ⟨NNT : 2018LORR0020⟩. ⟨tel-01877392⟩

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