Etablissement et évolution des interfaces lors du soudage diffusion

International audienceLa genèse des microstructures des interfaces soudées diffusées implique plusieurs mécanismes qui ont lieu simultanément et dont le développement au cours du cycle de soudage dépend des paramètres appliqués et des propriétés des surfaces initiales. L'élimination des pores est obtenue par la plastification immédiate des aspérités sous l'effet de la pression, leur fluage et finalement la diffusion. Certains alliages sont très sensibles à l'oxygène résiduel et forment facilement des oxydes ou des carbures en surface, au chauffage. L'évolution globale du volume du matériau, en particulier le grossissement de grain, affecte aussi l'interface mais celle-ci ne peut disparaître si elle présente des défauts susceptibles d'épingler les joints de grains

Environmental characterisation of retification process by-products (liquid and gaseous wastes)

6th International Symposium “Environment and Wood Preservation” Cannes-Mandelieu, France 7-8 February 2005 14 pagesIn order to reduce environmental risks during the service life of the treated wood and to find new alternative developments on the durability of wood, some research and technology development have been made on thermal treatment. The retification process is one of these processes. The retification process induces chemical modification of the lignin and cellulosic components and modifies the intrinsic properties of wood : efficient increases the durability against fungi and insects, increases of the dimensional stability, decrease of the mechanical properties. The interest of this process is to reduce the environmental impact during the service life. In order to confirm the high interest of this process for the reduction of the environmental impact, an environmental characterisation of wastes on pilot plant have been carried out. Chemical analysis on gaseous and liquid effluents have been performed. An energetic assessment has been realised. The results indicate the high interest of this process in terms of possible biodegradable wastes and chemical valorisation interest, interest on energetic consumption in comparison with other wood processing treatment, interest on using retification treated wood in flooring according to indoor air quality requirements

Full field modeling of recrystallization and grain growth thanks to a level set approach: towards modeling by industry

International audienceMetal forming modeling can be predictive only if the strain rate, strain and temperature dependency of the flow behaviour are correctly described. The mechanical properties and behaviour of metallic materials mainly depends on the content and structure of dislocation network, this points out the need to incorporate microstructure concepts into the numerical models. The goal is to correctly describe the main physical mechanisms occurring in metals during thermomechanical processes i.e. work-hardening, recovery, grain boundary migration, nucleation and grain growth related to dynamic, static or metadynamic recrystallization. Macroscopic and homogenized models are widely used in the industry, mainly due to their low computational cost. If this mean field framework is quite convenient, it can be synonymous, for a given material, with a large amount of experiments with advanced laboratory devices. Moreover, the homogenization of the microstructure does not permit to capture some very local phenomena

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Grain growth simulation applied to diffusion welding: interface crossing by grain boundaries

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Reflexion Measurements for Inverse Characterization of Steel Diffusion Bonds Mechanical Properties

The present work describes a non-destructive testing method aimed at securing very high manufacturing quality of the innovative compact heat exchanger developed under the framework of the CEA R&D program dedicated to the Advanced Sodium Technological Reactor for Industrial Demonstration (ASTRID). The heat exchanger assembly procedure currently proposed involves high temperature and high pressure diffusion welding of stainless steel plates. The aim of the non-destructive method presented herein is to characterize the quality of the welds obtained through this assembly process. Based on a low-frequency model developed by Baik and Thompson [1], pulse-echo normal incidence measurements are calibrated according to a specific procedure and allow the determination of the welding interface stiffness using a nonlinear fitting procedure in the frequency domain. Performing the characterization of plates after diffusion welding using this method allows a useful assessment of the material state as a function of the diffusion bonding process.</p

SIMSODI Project : finite element modelling of diffusion bonding by level-set method applied to interface crossing

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Maîtrise du grossissement de grain lors du soudage diffusion homogène de l'acier X2CrNiMo17-12-2 : problématique et apports de la simulation

International audienceLe soudage diffusion permet la fabrication d’échangeurs de chaleur compacts dans lesquels les circuits de fluide sont séparés par des parois fines. On présente et on illustre ici l’intérêt de la simulation du grossissement de grain lors du soudage diffusion en tant qu’outil permettant la maîtrise de la microstructure

How do men and women differ in their depressive symptomatology? A gendered network analysis of depressive symptoms in a French population-based cohort

International audienceBackground: The experience of depressive manifestations and the presentation of symptoms in clinical settings may differ in men and women. Despite the extensive literature, it remains unclear how depressive manifestations interact at symptom levels in men and women. First, we aimed to describe and compare depressive networks by sex. Second, we examined symptom connections to Clinical depression and Functional Limitations as a proxy of self-recognition of a depressive episode.Methods: We estimated networks from the 20 CES-D items in men and women from a large population-based French cohort. We computed centrality measures and ran comparisons. Then, we re-estimated two networks in men and women separately, adding, on the one hand, Clinical Depression and, on the other hand, Limitations due to a depressive episode.Results: Over 200,000 participants were included in this study. Women were twice as likely to have a previous diagnosis of depression. Sex-ratio was less pronounced (1,7:1) for Limitations due to depression. Centrality measures revealed similar symptom patterns. However, network structures differed between men and women. We found some symptom connections to Clinical depression and Limitations to be non-invariant according to sex.Limitations: Cross-sectional data does not capture the direction of the connections between symptoms and an eventual diagnosis. We lacked data about the diagnosis's context and could not account for other factors influencing depressive symptomatology.Conclusions: Network structures differed, suggesting gender-specific mechanisms in activating symptoms and depressive states. Addressing central symptoms evoking depressed moods with tailored interventions may serve to tackle depressive states in men and women

Sources d'hétérogénéité d'un assemblage par soudage par diffusion homogène de tôles en acier austénitique inoxydable

Ce document présente un aperçu des hétérogénéités de microstructure aux interfaces qui peuvent être rencontrées lors du soudage par diffusion homogène d'un assemblage de tôles. Un assemblage homogène a finalement été réalisé avec l'obtention de propriétés mécaniques très satisfaisantes. Pour finir, une piste de réflexion est apportée afin d'améliorer les propriétés des assemblages