Modélisation CA FE des structures de grains d'acier 316L en fusion laser lit de poudre

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Failure of hydrided zircaloy-4 fuel cladding tubes under RIA loading conditions

2-5 septembre 2008International audienceThe anisotropic viscoplastic behavior and the fracture of cold worked ...

Comparative study on Charpy specimen reconstitution techniques

International audienceReconstitution techniques are often used to allow material from previously fractured Charpy-V specimens to be reused for additional experiments. This paper presents a comparative experimental study of various reconstitution techniques and evaluates the feasibility of these methods for future use in shielded cells. The following techniques were investigated: arc stud welding, 6.0 kW CO2 continuous wave laser welding, 4.5 kW YAG continuous wave laser welding and friction welding. Subsize Charpy specimens were reconstituted using a 400 W YAG pulsed wave laser. The best result was obtained with arc stud welding; the resilience of the reconstituted specimens and the load-displacement curves agreed well with the reference specimens, and the temperature elevation caused by the welding process was limited to the vicinity of the weld. Good results were also obtained with friction welding; this process led to the best quality welds. Laser welding seems to have affected the central part of the specimens, thus leading to different resilience values and load-displacement curves

Behavior and failure of uniformly hydrided Zircaloy-4 fuel claddings between 25 °C and 480 °C under various stress states, including RIA loading conditions

International audienceThe anisotropic plastic behavior and the fracture of as-received and hydrided Cold-Worked Stress Relieved Zircaloy-4 cladding tubes are investigated under thermal-mechanical loading conditions representative of Pellet-Clad Mechanical Interaction during Reactivity Initiated Accidents in Pressurized Water Reactors. In order to study the combined effects of temperature, hydrogen content, loading direction and stress state, Axial Tensile, Hoop Tensile, Expansion Due to Compression and hoop Plane Strain Tensile tests are performed at room temperature, 350 °C and 480 °C on the material containing various hydrogen contents up to 1200 wt. ppm (hydrides are circumferential and homogeneously distributed). These tests are combined with digital image correlation and metallographic and fractographic observations at different scales. The flow stress of the material decreases with increasing temperature. The material is either strengthened or softened by hydrogen depending on temperature and hydrogen content. Plastic anisotropy depends on temperature but not on hydrogen content. The ductility of the material decreases with increasing hydrogen content at room temperature due to damage nucleation by hydride cracking. The plastic strain that leads to hydride fracture at room temperature decreases with increasing hydrogen content. The influence of stress triaxiality on hydride cracking is negligible in the studied range. The influence of hydrogen on material ductility is negligible at 350 °C and 480 °C since hydrides do not crack at these temperatures. The ductility of the material increases with increasing temperature. The evolution of material ductility is associated with a change in both the macroscopic fracture mode of the specimens and the microscopic failure mechanisms

High temperature expansion due to compression test for the determination of a cladding material failure criterion under RIA loading conditions

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A model to describe the anisotropic viscoplastic mechanical behavior of fresh and irradiated Zircaloy-4 fuel claddings under RIA loading conditions

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The PROMETRA Program: Fuel Cladding Mechanical Behavior under High Strain Rate

International audienceAn assessment of the mechanical properties of the highly irradiated fuel claddings under high strain rate has been carried out in the framework of the PROMETRA program undertaken by the French Institut de Radioprotection et de Sûreté Nucléaire in collaboration with Electricité de France and Commissariat à l’Energie Atomique (CEA). Three types of tests, including burst tests, hoop and axial tensile tests, have been performed at CEA-Saclay hot laboratories to determine the cladding tensile properties to use in the SCANAIR code. The prototypicality of each test with regard to the reactivity-initiated accident loading conditions can be addressed and analyzed in terms of strain or stress ratio. The high-strain-rate ductile mechanical properties of irradiated ZIRLO and M5 alloys derived from the PROMETRA program and their comparison to the stress-relieved irradiated Zircaloy-4 are reported. Then, the clad brittle behavior, in particular for highly corroded or spalled Zircaloy-4 cladding, is investigated

Ductility and Failure Behaviour of both Unirradiated and Irradiated Zircaloy-4 Cladding Using Plane Strain Tensile Specimens

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