Auswahl der wissenschaftlichen Literatur zum Thema „Fissuration assistée par l'oxydation“
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Zeitschriftenartikel zum Thema "Fissuration assistée par l'oxydation"
Sar, B. E., Y. Charles, P. Jouinot und M. Gasperini. „Simulation numérique de la fissuration assistée par l’hydrogène de « l’essai de disque »“. Matériaux & Techniques 99, Nr. 1 (2011): 141–44. http://dx.doi.org/10.1051/mattech/2011041.
Der volle Inhalt der QuelleDissertationen zum Thema "Fissuration assistée par l'oxydation"
Milanese, Julien. „Rupture intergranulaire assistée par l'oxydation et corrosion sous contrainte de produits minces en alliage 718 : rôle de la microstructure et de la chimie des joints de grains“. Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0054.
Der volle Inhalt der QuelleDue to its good resistance to Stress Corrosion Cracking (SCC), some of the components of nuclear assemblies of Pressurized Water Reactors (PWR) are made of alloy 718. Nevertheless, the current trend is increasing the liability and the safety of nuclear plants and needs a further understanding of the SCC mechanism of the material. Framatome is also considering a modification of the processing route of the strips used for the manufacturing of these components in order to improve the SCC resistance of the alloy 718. To better understand the SCC mechanism and support the solution undertaken, the influence of the metallurgical state on the damaging process must be investigated. The influences of the precipitation of phase and cold working on the susceptibility to intergranular cracking of the alloy were examined and the deformation mechanism at grain boundaries identified. It was shown that these two features were beneficial and improve the cracking resistance of the alloy but could not provide full desensitization when taken separately. Furthermore, grain boundary sliding was identified on the material susceptible to SCC whereas it is partially suppressed on the resistant one. From these observations, a mechanism for the initiation of intergranular cracks based on grain boundary sliding has been proposed. This work is a valuable contribution for the better understanding of the SCC mechanism of the alloy 718 and provides an explanation to the higher cracking resistance of the material derived from the new processing route. In addition, the relevance of the industrial solution to suit the problematic encountered was put forward
Bulidon, Nicolas. „Etude de la fissuration assistée par l'environnement des aciers peu alliés en situation de stockage géologique des déchets radioactifs“. Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI046/document.
Der volle Inhalt der QuelleThe aim of the work is to assess the susceptibility to environmental assisted cracking (EAC) of steels used for the deep geological storage of radioactive waste. The storage concept is based on the encapsulation of the waste in a carbon steel containers then placed in micro-tunnels drilled 500 meter deep in Clay. These micro-tunnels are built with a micro-alloyed casing steel. Recently, the storage concept has evolved with the injection of a cementitious bentonite grout between the clay and the casing to balance the potential acidity resulting from the excavation of the micro-tunnels and the gradual saturation of rock with water. Effect of this grout on the risk of corrosion and EAC is also evaluated in the PhD work. In the mild disposal environment considered (pH close to neutrality, low carbonate content), formation of a corrosion product scale composed of siderite and magnetite has been identified. This scale leads to a pseudo-passive state of both steel grades with thus a possible risk of EAC. The risk of EAC was thus first studied and a material selection for the disposal concept was thus first made accordingly. The protective nature of the siderite/magnetite corrosion scale was then studied and reproduced in laboratory using electrochemical techniques. This work allowed for the evaluation of the resistance of each selected steel with respect to general corrosion and EAC. The results did not underlined significant cracking susceptibility of the considered steel grades. Under deposit corrosion seems to be the main form of attack in aerated waste disposal environments but the influence of the presence of low oxygen levels has to be further explored
Le, Friant David. „Fissuration assistée par l'hydrogène et corrosion sous contrainte des aciers de pipelines : apports de l'étude des mécanismes de fissuration à la compréhension de l'endommagement de service et à la définition d'un test de classification“. ENSMP, 2000. http://www.theses.fr/2000ENMP0984.
Der volle Inhalt der QuelleRiad, Soukaina. „Vers une modélisation de la corrosion sous contrainte assistée par l'irradiation du superalliage 718“. Electronic Thesis or Diss., Ecole centrale de Nantes, 2022. http://www.theses.fr/2022ECDN0039.
Der volle Inhalt der QuelleInconel 718 alloy is renowned for having excellent corrosion resistance, very high mechanical strength and good resistance to irradiation. Thus, it is a material of choice within a nuclear power reactor for parts subjected to extreme stresses (springs, retaining systems,...). However, failures in service have been observed in this material under irradiationassisted stress corrosion cracking phenomenon. This thesis aims to bring new elements of understanding of this complex phenomenon from the point of view of numerical modeling. The stress corrosion cracking process is modeled by the phase field fracture method. A unified implementation, able to deal with inter and intergranular fracture, is proposedand allows to couple efficiently different scales of work (from continuous medium to polycrystal) and different physics (mechanics of continuous and generalized media and internal oxidation). This modeling allows to propose simulations of the complex stages of stress corrosion cracking, namely initiation, coalescence and propagation
Durif, Emilien. „Caractérisation du couplage mécano-électrochimique en pointe de fissure lors de la fissuration assistée par corrosion sous contrainte : cas du Zircaloy-4 en milieu aqueux halogéné“. Phd thesis, INSA de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00759340.
Der volle Inhalt der QuelleBizot, Patrice. „Vers un système expert de conception de mécanismes réactionnels complexes en phase gazeuse : application à la pyrolyse et à l'oxydation de composés organiques“. Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL102N.
Der volle Inhalt der QuelleHajj, Viviane. „Transfert couplé électron/proton et coupure de liaisons dans les systèmes bio-inspirés : études mécanistiques par électrochimie de l'oxydation d'une paire guanine-cytosine et de la coupure réductrice de liaison oxygène-oxygène assistée en présence d'un groupe donneur de proton“. Paris 7, 2011. https://tel.archives-ouvertes.fr/tel-00712330.
Der volle Inhalt der QuelleThe electron transfer associated with proton transfer or bond breaking is an important process often presented in naturel and biological System. Understanding the mechanistic issues involved in the operation of these Systems allows us to understand, imitate and exploit them. Two bio-inspired Systems have been studied by direct electrochemistry, the oxidation of a guanine paired to a cytosine with hydrogen bonds and the reduction of a cycloperoxide assisted by the presence of a proton donnor group. The match between DMA bases through hydrogen bonding has no effect on the kinetic and thermodynamic of the oxidation of a guanine. The reaction is kinetically controlled by the first stage of electronic transfer and the mechanism involved is sequentiel. The reductive cleavage of the O-O bond of the cycloperoxide assisted by the presence of a proton donor group is compared to another System in which the carboxylic acid function is replaced by a methoxy group. An offset of 700 mV was observed between the pic potential of both compounds indicating that the gain offered by the protonation step is expressed in the kinetic of the reaction. Consequently the dissociative electron transfer and the proton transfer are al concerted. A new simplified kinetic model was established to describe the dynamics of such a mechanism called « all in concert »
Nguejio, Nguimatsia Josiane. „Processus diffusionnels à l'origine de l'évolution de la composition d’un alliage au cours de l'oxydation sélective en pointe de fissures intergranulaires. Application à la CSC de l'Alliage 600 en milieu primaire des REP“. Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLEM054/document.
Der volle Inhalt der QuelleStress Corrosion Cracking (SCC) of nickel base alloys is one of the major degradation phenomena in the primary circuit of Pressurized Water Reactors (PWR). Understanding the SCC mechanism is a key issue for the extension of reactor lifetime.A SCC model based on a selective and asymmetrical oxidation of the grain boundary ahead of the crack tip has been proposed in previous studies. Adjacent to this oxide, a chromium-depleted area is observed exclusively in one of the two grains adjacent to the grain boundary. As oxygen transport is found to be faster than chromium diffusion in the alloy, the latter is assumed to be the rate-limiting step of crack propagation. Nevertheless, the mechanism responsible for chromium depletion is still under debate. Indeed, the lattice and the grain boundary diffusion coefficients of chromium in nickel-based alloys at 350°C are not high enough to explain the chromium depletion magnitudes measured in the literature. Accordingly, factors accelerating chromium diffusion in the alloy ahead of the SCC crack tip should exist. Thus, two assumptions have been proposed in this work: plasticity-enhanced chromium diffusion and diffusion-induced grain boundary migration (DIGM).The aim of this study is to confront these two assumptions by combining both experiments and modeling in order to explain chromium depleted areas observed at the SCC crack tip.Thus, diffusion tests under loading were performed in order to study the effect of plastic deformation on chromium diffusion. Plasticity-enhanced diffusion is evidenced. A relationship between the diffusion coefficient and strain rate has been established leading to a 106-fold increase of the diffusion coefficient at 350°C. In addition, thermal treatments and oxidation tests have shown that diffusion-induced grain boundary migration occurs in Ni-Cr alloys. DIGM leads to dissymmetric Cr-depleted areas, observed in the wake of the moving grain boundary
Malheiros, Livia Cupertino. „Study of Structure, Hydrogen Diffusion and Trapping, Plasticity and Fracture towards the Comprehension of Hydrogen-Assisted Cracking of High-Strength Low-Alloy Martensitic Steels“. Thesis, La Rochelle, 2020. http://www.theses.fr/2020LAROS022.
Der volle Inhalt der QuelleThe challenge of developing steels for sour service oil country tubular goods (OCTG) with mechanical strengthhigher and higher maintaining a sufficient resistance to sulfide stress cracking (SSC) motivates this researchtowards a better understanding of the hydrogen embrittlement of low-alloy tempered martensitic steels. Structuralcharacterization is performed by multiple techniques including SEM-EBSD, TEM, DSC, synchrotron andconventional XRD. The results are related to diffusion and trapping parameters from electrochemical permeation(EP) and thermal desorption spectroscopy (TDS), being mostly discussed in terms of dislocation density, vacancyconcentration, yield strength, composition and tempering temperature for ten martensitic steels. Tensile, loadingunloadingand stress-relaxation tests are completed without hydrogen, after hydrogen pre-charging and desorption,and under hydrogen flux to evaluate the impact of hydrogen trapping and mobility on the hydrogen-plasticityinteractions. For the test under hydrogen flux, an electrochemical permeation cell is built on a mechanical testingmachine, which allows continuous monitoring of the global hydrogen flux and mechanical loading during thetensile test of notched and unnotched specimens. By varying the notch geometries and the cathodic polarizationcurrent densities, we tested the susceptibility of the steels to hydrogen-assisted cracking under various intensitiesof hydrogen flux and concentration for several mechanical states. Tests on pre-charged specimens revealed thatdeeply trapped hydrogen has a minor impact on the mechanical behavior and fracture, whereas mobile hydrogenleads to brittle quasi-cleavage fracture at the hydrogen entry surfaces. The permeation test under tensile loadingresults are incorporated into finite elements modelling (FEM). Macroscopic and local (from FEM) conditions forthe development of hydrogen-assisted quasi-cleavage fracture are evaluated, as well as the sensitivity of thesethreshold conditions (stress, plastic strain, hydrogen flux and concentration) to the severity of the applied cathodicpolarization
Konferenzberichte zum Thema "Fissuration assistée par l'oxydation"
Fregonese, M. „Détection et quantification des phénomènes de fissuration assistée par l'environnement“. In PlastOx 2007 - Mécanismes et Mécanique des Interactions Plasticité - Environnement. Les Ulis, France: EDP Sciences, 2009. http://dx.doi.org/10.1051/ptox/2009015.
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