Etude de l'influence de la convection naturelle et forcée sur le processus de la solidification (cas d'un alliage métallique binaire.)

Ce travail se situé dans la perspective d'un contrôle de la structure de solidification des alliages métalliques sous l'effet de la convection naturelle et forcée afin d'améliorer à terme la maîtrise des microstructures de solidification grâce à un brassage électromagnétique efficace permettant d'avoir une homogénéisation du bain liquide qui par la suite peut améliorer la microstructure finale de l'alliage. La possibilité retenue dans ce travail est de réaliser ce brassage sans contact avec la solution liquide (alliage sous fusion) et sans pollution par d'autres éléments en utilisant un brassage par la force de Lorentz. L'objet de la thèse comporte une étude théorique à la fois expérimentale basée sur une installation expérimentale particulièrement documentée et instrumentée, développée au laboratoire SIMAP/EPM à Grenoble, nommée AFRODITE. Ce dispositif expérimental permet de fournir des données de quantitatives et qualitatives sur le processus de solidification des alliages métalliques. Ces données sont nécessaires à la contribution aux études menées sur la solidification des alliages métallique et enrichir la base des donnée des modèles numériques développés pour prédire les défauts liés à la solidification. L'alliage choisi dans notre travail est l'étain-plomb, vue sa basse température de fusion. Les expériences envisagées visent à étudier l'effet de deux modes de configuration dynamique sur la solidification de l'alliage Sn-Pb: la convection thermosolutale avec la variation de deux paramètres essentiels (la vitesse de refroidissement et la différence de température expérimentale) et la convection forcée par l'utilisation de plusieurs modes de brassage électromagnétique. Cette étude s'intéresse en particulier à la caractérisation des macrostructures et les défauts liés à la macroségrégation. L'originalité de l'étude vise à mesurer in situ les températures instantanées. Ceci nous a permis d'évaluer l'évolution du transfert thermique due à la convection naturelle/forcée, ainsi que leurs influence sur le processus de la solidification sous différents aspects. L'analyse post-mortem de l'alliage métallique, fournit la structure de solidification et la distribution des ségrégations à différentes échelles (mésoscopique et macroscopique).This work is situated in the context of control of the solidification of metallic alloys structure under the effect of natural and forced convection to enhance control of solidification microstructures term through effective electromagnetic stirring to have a homogenizing the liquid which may subsequently improve the final microstructure of the alloy. The possibility considered in this work is to achieve this stirring without contacting the liquid solution (alloy in fusion) and pollution by other elements using a patch by the Lorentz force. The purpose of the thesis consists both a theoretical and experimental study based on an experimental setup particularly documented and instrumented developed / EPM SIMAP laboratory in Grenoble, named AFRODITE. The experimental device used to provide quantitative and qualitative data on the process of solidification of metallic alloys. These data are necessary for the contribution to studies on the solidification of metallic alloys and enrich the data base developed numerical models to predict defects related to solidification. The alloy selected from our work is tin-lead, for its low melting temperature. The proposed experiments are designed to study the effect of two types of dynamic configuration on the solidification of Sn-Pb alloy: the thermosolutal convection with the variation of two essential parameters (cooling rate and the difference in experimental temperature) and forced convection by the use of several modes of electromagnetic stirring. This study is particularly interested in the characterization of macrostructures and defects related to macrosegregation. The originality of this study is to measure in situ instantaneous temperatures. This allowed us to assess the evolution of the heat transfer due to natural / forced convection and their influence on the process of solidification in different aspects. The post-mortem analysis of the metal alloy provides the solidification structure and distribution of segregation at different scales (mesoscopic and macroscopic).SAVOIE-SCD - Bib.électronique (730659901) / SudocGRENOBLE1/INP-Bib.électronique (384210012) / SudocGRENOBLE2/3-Bib.électronique (384219901) / SudocSudocFranceF

Experimental investigation of the natural and forced convection on solidification of Sn-3wt. %Pb alloy using a benchmark experiment

International audienceWe deal with the development of a solidification benchmark experiment in order to investigate the structure formation as well as solute macro-mesosegregation, by means of a well-controlled solidification experiment. The experiment consists in solidifying a rectangular ingot of Sn-3wt.%Pb alloy, by using two lateral heat exchangers which allow extraction of the heat flux from one or two vertical sides of the sample. The domain is a quasi two dimensional parallepipedic ingot (100x60x10) mm. The temperature difference ΔT between the two lateral sides is 40 K and the cooling rate CR= 0.03 K/s. The instrumentation consists in recording the instantaneous temperature maps by means of an array of 50 thermocouples in order to provide the time evolution of the isotherms. After each experiment the patterns of the segregations have been obtained by X-ray radiograph and confirmed by eutectic fraction measurements. The local solute distribution determined by means of induction coupled plasma analysis is provided. The originality of the present study is to examine the effect of the forced convection driven by a travelling magnetic field (TMF) induced by a linear inductor located on the bottom part of the sample. A periodically reversed stirring with a modulation frequency equal to 0.5 Hz stirring have been investigated. This study allows us to evaluate the evolution due to the forced convection induced by a TMF field, as well as its influence on the initial conditions, the solidification macrostructure and the segregation behavior. Measurements of the velocity field by ultrasonic Doppler velocimetry (UDV) method in a Ga-In-Sn pool were performed and transposed to the tin-lead alloy case before solidification. Post-mortem patterns of the macro-mesosegregations have been obtained by X-ray radiography. The results show the transport effects of the flow on both the macrosegregations and the channel formation. The reversal of the TMF produces a decrease of the level of mesosegregations, namely channel formation

Study of the influence of natural and forced convection on the solidification of a binary metal alloy.

Ce travail se situé dans la perspective d'un contrôle de la structure de solidification des alliages métalliques sous l'effet de la convection naturelle et forcée afin d'améliorer à terme la maîtrise des microstructures de solidification grâce à un brassage électromagnétique efficace permettant d'avoir une homogénéisation du bain liquide qui par la suite peut améliorer la microstructure finale de l'alliage. La possibilité retenue dans ce travail est de réaliser ce brassage sans contact avec la solution liquide (alliage sous fusion) et sans pollution par d'autres éléments en utilisant un brassage par la force de Lorentz. L'objet de la thèse comporte une étude théorique à la fois expérimentale basée sur une installation expérimentale particulièrement documentée et instrumentée, développée au laboratoire SIMAP/EPM à Grenoble, nommée AFRODITE. Ce dispositif expérimental permet de fournir des données de quantitatives et qualitatives sur le processus de solidification des alliages métalliques. Ces données sont nécessaires à la contribution aux études menées sur la solidification des alliages métallique et enrichir la base des donnée des modèles numériques développés pour prédire les défauts liés à la solidification. L'alliage choisi dans notre travail est l'étain-plomb, vue sa basse température de fusion. Les expériences envisagées visent à étudier l'effet de deux modes de configuration dynamique sur la solidification de l'alliage Sn-Pb: la convection thermosolutale avec la variation de deux paramètres essentiels (la vitesse de refroidissement et la différence de température expérimentale) et la convection forcée par l'utilisation de plusieurs modes de brassage électromagnétique. Cette étude s'intéresse en particulier à la caractérisation des macrostructures et les défauts liés à la macroségrégation. L'originalité de l'étude vise à mesurer in situ les températures instantanées. Ceci nous a permis d'évaluer l'évolution du transfert thermique due à la convection naturelle/forcée, ainsi que leurs influence sur le processus de la solidification sous différents aspects. L'analyse post-mortem de l'alliage métallique, fournit la structure de solidification et la distribution des ségrégations à différentes échelles (mésoscopique et macroscopique).This work is situated in the context of control of the solidification of metallic alloys structure under the effect of natural and forced convection to enhance control of solidification microstructures term through effective electromagnetic stirring to have a homogenizing the liquid which may subsequently improve the final microstructure of the alloy. The possibility considered in this work is to achieve this stirring without contacting the liquid solution (alloy in fusion) and pollution by other elements using a patch by the Lorentz force. The purpose of the thesis consists both a theoretical and experimental study based on an experimental setup particularly documented and instrumented developed / EPM SIMAP laboratory in Grenoble, named AFRODITE. The experimental device used to provide quantitative and qualitative data on the process of solidification of metallic alloys. These data are necessary for the contribution to studies on the solidification of metallic alloys and enrich the data base developed numerical models to predict defects related to solidification. The alloy selected from our work is tin-lead, for its low melting temperature. The proposed experiments are designed to study the effect of two types of dynamic configuration on the solidification of Sn-Pb alloy: the thermosolutal convection with the variation of two essential parameters (cooling rate and the difference in experimental temperature) and forced convection by the use of several modes of electromagnetic stirring. This study is particularly interested in the characterization of macrostructures and defects related to macrosegregation. The originality of this study is to measure in situ instantaneous temperatures. This allowed us to assess the evolution of the heat transfer due to natural / forced convection and their influence on the process of solidification in different aspects. The post-mortem analysis of the metal alloy provides the solidification structure and distribution of segregation at different scales (mesoscopic and macroscopic)

Etude de l'influence de la convection naturelle et forcée sur le processus de la solidification : cas d'un alliage métallique binaire.

This work is situated in the context of control of the solidification of metallic alloys structure under the effect of natural and forced convection to enhance control of solidification microstructures term through effective electromagnetic stirring to have a homogenizing the liquid which may subsequently improve the final microstructure of the alloy. The possibility considered in this work is to achieve this stirring without contacting the liquid solution (alloy in fusion) and pollution by other elements using a patch by the Lorentz force. The purpose of the thesis consists both a theoretical and experimental study based on an experimental setup particularly documented and instrumented developed / EPM SIMAP laboratory in Grenoble, named AFRODITE. The experimental device used to provide quantitative and qualitative data on the process of solidification of metallic alloys. These data are necessary for the contribution to studies on the solidification of metallic alloys and enrich the data base developed numerical models to predict defects related to solidification. The alloy selected from our work is tin-lead, for its low melting temperature. The proposed experiments are designed to study the effect of two types of dynamic configuration on the solidification of Sn-Pb alloy: the thermosolutal convection with the variation of two essential parameters (cooling rate and the difference in experimental temperature) and forced convection by the use of several modes of electromagnetic stirring. This study is particularly interested in the characterization of macrostructures and defects related to macrosegregation. The originality of this study is to measure in situ instantaneous temperatures. This allowed us to assess the evolution of the heat transfer due to natural / forced convection and their influence on the process of solidification in different aspects. The post-mortem analysis of the metal alloy provides the solidification structure and distribution of segregation at different scales (mesoscopic and macroscopic).Ce travail se situé dans la perspective d'un contrôle de la structure de solidification des alliages métalliques sous l'effet de la convection naturelle et forcée afin d'améliorer à terme la maîtrise des microstructures de solidification grâce à un brassage électromagnétique efficace permettant d'avoir une homogénéisation du bain liquide qui par la suite peut améliorer la microstructure finale de l'alliage. La possibilité retenue dans ce travail est de réaliser ce brassage sans contact avec la solution liquide (alliage sous fusion) et sans pollution par d'autres éléments en utilisant un brassage par la force de Lorentz. L'objet de la thèse comporte une étude théorique à la fois expérimentale basée sur une installation expérimentale particulièrement documentée et instrumentée, développée au laboratoire SIMAP/EPM à Grenoble, nommée AFRODITE. Ce dispositif expérimental permet de fournir des données de quantitatives et qualitatives sur le processus de solidification des alliages métalliques. Ces données sont nécessaires à la contribution aux études menées sur la solidification des alliages métallique et enrichir la base des donnée des modèles numériques développés pour prédire les défauts liés à la solidification. L'alliage choisi dans notre travail est l'étain-plomb, vue sa basse température de fusion. Les expériences envisagées visent à étudier l'effet de deux modes de configuration dynamique sur la solidification de l'alliage Sn-Pb: la convection thermosolutale avec la variation de deux paramètres essentiels (la vitesse de refroidissement et la différence de température expérimentale) et la convection forcée par l'utilisation de plusieurs modes de brassage électromagnétique. Cette étude s'intéresse en particulier à la caractérisation des macrostructures et les défauts liés à la macroségrégation. L'originalité de l'étude vise à mesurer in situ les températures instantanées. Ceci nous a permis d'évaluer l'évolution du transfert thermique due à la convection naturelle/forcée, ainsi que leurs influence sur le processus de la solidification sous différents aspects. L'analyse post-mortem de l'alliage métallique, fournit la structure de solidification et la distribution des ségrégations à différentes échelles (mésoscopique et macroscopique)

Multiscale statistical analysis of the tin-lead alloy solidification process

International audienceThis paper presents a quasi-two-dimensional solidification benchmark experiment with controlled thermal boundary conditions. The experiment consists in solidifying a rectangular ingot of Sn-3wt.%Pb using two lateral heat exchangers to extract the heat flux from one or both vertical sides of the sample. The aim is to assess the reproducibility of the solidification experiments performed under rigorously identical conditions. The temperature difference (Delta T) between the two vertical sides is 40 K and the cooling rate (CR) is 0.03 K/s. This slow-cooling condition favours segregation formation. A lattice of fifty thermocouples placed on the front of the sample between the two vertical sides is used to determine the instantaneous temperature distribution. During solidification, the time evolution of the temperature field is recorded, and analyzed. This allows us to estimate the time evolution of the temperatures due to natural convection and assess the velocity field, the solidification macrostructure and the segregation behaviour. Post-mortem segregation patterns are obtained both by X-ray radiography and induction coupled plasma analysis. The recorded data is analyzed statistically. An ensemble average procedure is applied to both instantaneous temperature and post-mortem composition measurements. This makes it possible to determine the mean values of the solidification parameters as well as their standard deviations. Temperature fluctuation standard deviations are deterministic and characterize the solidification dynamics. Among other results, it is shown that mesoscale segregation locations are not fully predictable. (C) 2016 Elsevier Masson SAS. All rights reserved

3D numerical simulation and experimental investigation of pure tin solidification under natural and forced convection

International audienc

Numerical modeling of a benchmark experiment on equiaxed solidification of a Sn–Pb alloy with electromagnetic stirring and natural convection

International audienceA three-phase volume averaged equiaxed model is applied to simulation of an experiment on solidification of the binary alloy Sn-10wt% Pb subjected to the electromagnetic stirring. The experiment, whose description was published earlier, was performed in a parallelepiped cavity under controlled cooling conditions and with real-time two-dimensional temperature measurement over a lateral surfac

Modeling Dendrite Coarsening and Remelting during Directional Solidification of Al-06wt.%Cu Alloy

Research efforts have been dedicated to predicting microstructural evolution during solidification processes. The main secondary arm spacing controls the mushy zone’s permeability. The aim of the current work was to build a simple sub-grid model that describes the growth and coarsening of secondary side dendrite arms. The idea was to reduce the complexity of the curvature distribution with only two adjacent side arms in concurrence. The model was built and applied to the directional solidification of Al-06wt%Cu alloy in a Bridgman experiment. The model showed its effectiveness in predicting coarsening phenomena during the solidification of Al-06wt%Cu alloy. The results showed a rapid growth of both arms at an earlier stage of solidification, followed by the remelting of the smaller arm. In addition, the results are in good agreement with an available time-dependent expression which covers the growth and coarsening. Such model can be implemented as a sub-grid model in volume average models for the prediction of the evolution of the main secondary arms spacing during macroscopic solidification processes