1,026 research outputs found
Influence des traitements thermiques à haute température sur l'évolution de la texture et de la microstructure des soudures d'acier inoxydable duplex 2205
No full textThis work deals with the study of the texture and microstructure evolution during welding and subsequent annealing treatment of 2205 duplex stainless steel. Microstructural examination showed the presence of higher ferrite amount in the heat affected zone (HAZ), while higher amount of austenite was recorded in the centre region of the weld metal. Annealing treatment at temperature range of 800-1000°C resulted in a precipitation of σ phase and M23C6 chromium carbides at the γ/δ interfaces that were found as preferential precipitation sites. Above 1050 °C, the volume fraction of δ ferrite increases with annealing temperature. Optimal mechanical properties and accepted γ/δ ratio throughout the weld regions corresponds to annealing at 1050 °C. Aging at 850 °C after solution treatment showed that increasing the solution treatment temperature from 1050 to 1250°C delays the σ phase formation and favours the precipitation of intragranular secondary austenite γ2. The simulation of the σ phase precipitation kinetic in the base metal, HAZ and weld metal indicates a good agreement between the experimental fitted data and the modified J.M.A model. The results indicate also a marked sensitivity of the σ phase precipitation kinetic to the solution treatment temperature. Texture analysis using EBSD technique led to determine the exact orientation relationship between austenite and ferrite in the weld metal as a 44.2 rotation around axis. While no major change was observed in the HAZ and base metal texture, some scatter of the orientation relationship determined in the base metal was registered after annealing at 1250°C because of the grain morphological change.Ce travail traite de l'évolution de la texture et de la microstructure dans les soudures d'acier inoxydable duplex 2205 traitées thermiquement. L'analyse microstructurale a montré que la ZAT est caractérisée par une forte teneur en ferrite alors que le centre du métal fondu contient plus d'austénite. Les traitements thermiques effectués dans le domaine 800-1000°C ont causé la précipitation de la phase σ et des carbures de chrome M23C6 aux interfaces γ / δ qui sont les sites privilégiés de germination. Au-delà de 1050°C la fraction volumique de la ferrite augmente avec la température. Les propriétés mécaniques optimales du joint soudé sont obtenues suite à un traitement d'hypertrempe à 1050 °C pendant 1h. Le passage de la température d'hypertrempe de 1050 à 1250 °C retarde la précipitation de la phase σ et favorise celle de l'austénite secondaire γ2. L'étude de la cinétique de précipitation de la phase σ dans les différentes zones de la soudure montre que celle-ci suit le modèle modifié de JMA. Les résultats obtenus montrent une dépendance significative de la précipitation de la phase σ par rapport à la température d'hypertrempe. L'analyse par EBSD de la texture cristallographique du métal fondu a permis de déterminer la relation d'orientation exacte entre l'austénite et la ferrite comme étant une rotation de 44.2° autour d'un axe . La texture du métal de base reste quasiment stable suite à l'opération de soudage et aux traitements thermiques effectués au moment où une petite dispersion vient perturber légèrement la relation d'orientation dans le métal fondu
Influence des traitements thermiques à haute température sur l'évolution de la texture et de la microstructure des soudures d'acier inoxydable duplex 2205
No full textThis work deals with the study of the texture and microstructure evolution during welding and subsequent annealing treatment of 2205 duplex stainless steel. Microstructural examination showed the presence of higher ferrite amount in the heat affected zone (HAZ), while higher amount of austenite was recorded in the centre region of the weld metal. Annealing treatment at temperature range of 800-1000°C resulted in a precipitation of σ phase and M23C6 chromium carbides at the γ/δ interfaces that were found as preferential precipitation sites. Above 1050 °C, the volume fraction of δ ferrite increases with annealing temperature. Optimal mechanical properties and accepted γ/δ ratio throughout the weld regions corresponds to annealing at 1050 °C. Aging at 850 °C after solution treatment showed that increasing the solution treatment temperature from 1050 to 1250°C delays the σ phase formation and favours the precipitation of intragranular secondary austenite γ2. The simulation of the σ phase precipitation kinetic in the base metal, HAZ and weld metal indicates a good agreement between the experimental fitted data and the modified J.M.A model. The results indicate also a marked sensitivity of the σ phase precipitation kinetic to the solution treatment temperature. Texture analysis using EBSD technique led to determine the exact orientation relationship between austenite and ferrite in the weld metal as a 44.2 rotation around axis. While no major change was observed in the HAZ and base metal texture, some scatter of the orientation relationship determined in the base metal was registered after annealing at 1250°C because of the grain morphological change.Ce travail traite de l'évolution de la texture et de la microstructure dans les soudures d'acier inoxydable duplex 2205 traitées thermiquement. L'analyse microstructurale a montré que la ZAT est caractérisée par une forte teneur en ferrite alors que le centre du métal fondu contient plus d'austénite. Les traitements thermiques effectués dans le domaine 800-1000°C ont causé la précipitation de la phase σ et des carbures de chrome M23C6 aux interfaces γ / δ qui sont les sites privilégiés de germination. Au-delà de 1050°C la fraction volumique de la ferrite augmente avec la température. Les propriétés mécaniques optimales du joint soudé sont obtenues suite à un traitement d'hypertrempe à 1050 °C pendant 1h. Le passage de la température d'hypertrempe de 1050 à 1250 °C retarde la précipitation de la phase σ et favorise celle de l'austénite secondaire γ2. L'étude de la cinétique de précipitation de la phase σ dans les différentes zones de la soudure montre que celle-ci suit le modèle modifié de JMA. Les résultats obtenus montrent une dépendance significative de la précipitation de la phase σ par rapport à la température d'hypertrempe. L'analyse par EBSD de la texture cristallographique du métal fondu a permis de déterminer la relation d'orientation exacte entre l'austénite et la ferrite comme étant une rotation de 44.2° autour d'un axe . La texture du métal de base reste quasiment stable suite à l'opération de soudage et aux traitements thermiques effectués au moment où une petite dispersion vient perturber légèrement la relation d'orientation dans le métal fondu
Social theory and the sociological imagination: an interview with Nigel Dodd (1 of 2)
No full textPart I of our interview with Nigel Dodd, interviewed by Riad Azar. Nigel Dodd is Professor in the Sociology Department at the LSE. He obtained his PhD from the University of Cambridge in 1991 on the topic of Money in Social Theory, and lectured at the University of Liverpool before joining the LSE in 1995. Nigel’s main interests are in the sociology of money, economic sociology and classical and contemporary social thought. He is author of The Sociology of Money and Social Theory and Modernity (both published by Polity Press). His most recent book, The Social Life of Money, was published by Princeton University Press in September 2014
Adapting the Rhetoric of Authentication of Riad Sattouf’s La Vie secrète des jeunes
No full textThe comic book series La Vie secrète des jeunes is a sardonic account of
French young people’s behaviours witnessed from the voyeuristic viewpoint
of its author-illustrator, Riad Sattouf. Despite its caricatural and non-photorealistic
visual style, the work conveys a strong sense of authenticity, mixing
truth claims borrowed from established non-fiction traditions (journalism,
autobiography and documentary). It is also a rare example of a non-fiction
comic turned into live action. This article considers the comic and its TV
adaptation, and discusses film’s ability to adapt an account of truth rooted
in comics ontology. The article first provides a theoretical structure that
details the intricacy of repeating the truth from comic to film. Second, it
highlights the way in which the comic develops its authenticity by constantly
reaffirming Sattouf’s presence and subjectivity. The article aims to show
that the adaptation anonymises this viewpoint in order to re-construct the
authenticity of its reality.</jats:p
Residual stresses of a magnesium alloy (AZ31) welded by the friction stir welding processes
No full textInternational audienceThe objective of this study was to evaluate the residual stresses of FSW welding magnesium alloys (AZ31). The results show that the FSW processes lead to the formation of several distinct zones with differing mechanical properties. The residual stresses evolution have been explained by the heterogeneous modifications of the microstructure particularly a marked decrease in the grain size, a high modification of the crystallographic texture and the different anisotropic properties resulting from plasticity induced by the FSW process
Construction et déconstruction de la masculinité hégémonique dans L’Arabe du futur 1 : Une jeunesse au Moyen-Orient (1978-1984) de Riad Sattouf
No full textThrough the analysis of the graphic novel L'Arabe du future 1. Une jeunesse au Moyen-Orient (1978-1985) by the Franco-Syrian cartoonist Riad Sattouf, this contribution aims to investigate the construction of hegemonic masculinity in Gaddafi's post-colonial Libya and Hafez al Assad's Syria. First, this study intends to track the stages of Riad's journey towards the achievement of hegemonic masculinity. In this context, a special focus will be laid on the construction of the mother's character through that of the father, thereby showing how the female character takes shape from the male perspective. Second and finally, it attempts to analyse how the author implements a deconstruction path of hegemonic masculinity by using certain rhetorical devices, namely irony, stereotype repetition and the adoption of his own perspective as a child
Influence des traitements thermiques à haute température sur l'évolution de la texture et de la microstructure des soudures d'acier inoxydable duplex 2205
No full textCe travail traite de l évolution de la texture et de la microstructure dans les soudures d acier inoxydable duplex 2205 traitées thermiquement. L analyse microstructurale a montré que la ZAT est caractérisée par une forte teneur en ferrite alors que le centre du métal fondu contient plus d austénite. Les traitements thermiques effectués dans le domaine 800-1000C ont causé la précipitation de la phase et des carbures de chrome M23C6 aux interfaces g / qui sont les sites privilégiés de germination. Au-delà de 1050C la fraction volumique de la ferrite augmente avec la température. Les propriétés mécaniques optimales du joint soudé sont obtenues suite à un traitement d hypertrempe à 1050 C pendant 1h. Le passage de la température d hypertrempe de 1050 à 1250 C retarde la précipitation de la phase et favorise celle de l austénite secondaire g2. L étude de la cinétique de précipitation de la phase dans les différentes zones de la soudure montre que celle-ci suit le modèle modifié de JMA. Les résultats obtenus montrent une dépendance significative de la précipitation phase par rapport à la température d hypertrempe. L analyse par EBSD de la texture cristallographique du métal fondu a permis de déterminer la relation d orientation exacte entre l austénite et la ferrite comme étant une rotation de 44.2 autour d un axe . La texture du métal de base reste quasiment stable suite à l opération de soudage et aux traitements thermiques effectués au moment où une petite dispersion vient perturber légèrement la relation d orientation dans le métal fondu.This work deals with the study of the texture and microstructure evolution during welding and subsequent annealing treatment of 2205 duplex stainless steel. Microstructural examination showed the presence of higher ferrite amount in the heat affected zone (HAZ), while higher amount of austenite was recorded in the centre region of the weld metal. Annealing treatment at temperature range of 800-1000C resulted in a precipitation of phase and M23C6 chromium carbides at the g/ interfaces that were found as preferential precipitation sites. Above 1050 C, the volume fraction of ferrite increases with annealing temperature. Optimal mechanical properties and accepted g/ ratio throughout the weld regions corresponds to annealing at 1050 C. Aging at 850 C after solution treatment showed that increasing the solution treatment temperature from 1050 to 1250C delays the phase formation and favours the precipitation of intragranular secondary austenite g2. The simulation of the phase precipitation kinetic in the base metal, HAZ and weld metal indicates a good agreement between the experimental fitted data and the modified J.M.A model. The results indicate also a marked sensitivity of the phase precipitation kinetic to the solution treatment temperature. Texture analysis using EBSD technique led to determine the exact orientation relationship between austenite and ferrite in the weld metal as a 44.2 rotation around axis. While no major change was observed in the HAZ and base metal texture, some scatter of the orientation relationship determined in the base metal was registered after annealing at 1250C because of the grain morphological change.PARIS13-BU Sciences (930792102) / SudocSudocFranceF
Radio frequency rectifiers for direct current-direct current power conversion
No full textThesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.Includes bibliographical references (p. 75-78).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.A significant factor driving the development of power conversion technology is the need to increase performance while reducing size and improving efficiency. In addition, there is a desire to increase the level of integration of DC-DC converters in order to take advantage of the cost and other benefits of batch fabrication techniques. While advances in the power density and integration of DC-DC converters have been realized through development of better active device technologies, much room for improvement remains in the size and fabrication of passive components. To achieve these improvements, a substantial increase in operating frequency is needed, since intermediate energy storage requirements are inversely proportional to frequency. Unfortunately, traditional power conversion techniques are ill-suited to handle this dramatic escalation of switching frequency. New architectures have been proposed which promise to deliver radical performance improvements while potentially reaching microwave frequencies. These new architectures promise to enable substantial miniaturization of DC-DC converters and to permit much a higher degree of integration. The principal effort of this thesis is the development of design and characterization methods for rectifier topologies amenable to use in the new architectures. A computational design approach allowing fast and accurate circuit analysis and synthesis is developed and applied, along with traditional analysis, to two demonstrative rectifier topologies. In addition, the application of coupled magnetic structures for parasitic mitigation is considered. Experimental implementations are investigated to verify analytic and computational results.by Riad Samir Wahby.M.Eng
Residual stresses of a magnesium alloy (AZ31) welded by the friction stir welding processes
No full textThe objective of this study was to evaluate the residual stresses of FSW welding magnesium alloys (AZ31). The results show that the FSW processes lead to the formation of several distinct zones with differing mechanical properties. The residual stresses evolution have been explained by the heterogeneous modifications of the microstructure particularly a marked decrease in the grain size, a high modification of the crystallographic texture and the different anisotropic properties resulting from plasticity induced by the FSW process
Microstructure, mechanical performance and wear behaviour of MMC (WC-W-Ni/Fe) obtained by infiltration
No full textWC-W-Ni-Fe composites were fabricated by infiltrating WC-5 W-5Ni porous preforms with a Cu-10Ni-6Sn binder alloy at 1180 °C. The study focused on the effects of Fe addition on the microstructural evolution and tribological performance of the composites. The infiltration produced dense materials with a heterogeneous microstructure composed of WC and W₂C carbides distributed within a dual-phase metallic matrix consisting of a Cu-rich phase and a NiSn intermetallic compound. The partial dissolution of Fe particles into the binder, enhanced particle rearrangement during solid-state heating, and led to the formation of ring-shaped WC and W distributions. However, both Ni and Fe induced partial decarburization of the carbides and favoured the precipitation of brittle (Fe,Ni)₃W₃C η-phase, preferentially at binder/carbide interfaces and within thermally induced cracks. Tribological testing under dry sliding conditions revealed that Fe-containing composites exhibited improved wear resistance than Fe-free composites, despite the formation of η-phase. The enhancement was attributed to an increased binder ductility and the formation of fracture-induced debris that protected the surface during sliding.Key research and development project of Jiangxi Province (20224BBE51041)Jiangxi Provincial Department of Education (GJJ2200819)Scientific Research Starting Foundation for Advanced Talents of Jiangxi University of Science and Technology (205200100636)Collaborative Innovation Center for Development and Utilization of Rare Metal Resources Co-sponsored by Ministry of Education and Jiangxi Province (JXUST-XTCX-2024-03)Depto. de Ingeniería Química y de MaterialesFac. de Ciencias QuímicasTRUEpu
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