Evolution des microstructures et textures locales par nitruration plasma de l'acier 316L. Répercussion sur sa durabilité en fatigue

Abstract : The present study concerns the surface and mechanical properties induced by specific low temperature (~400°C) plasma nitriding of an AISI 316L austenitic stainless steel largely used for structural component in nuclear and chemical industries. It focuses especially on its influence on the fatigue durability. The great advantages of this plasma nitriding process are to produce thick nitrided layers with a high concentration of nitrogen atoms in solid solution into the material and to preserve the stainless character of the substrate. As a consequence a new phase named expanded austenite or γN phase is formed and the lattice expansion associated with the high supersaturation of interstitial nitrogen atoms results in residual compressive stresses at the surface that exceed 2GPa. The surface is then strongly modified as a result of complex effects including some crystallographic plane rotation, plasticity and damage in some grains depending on their orientation. The considerable increase of hardness and wear resistance produced by plasma nitriding of austenitic stainless steels is now well documented but there are practically no data on the influence on fatigue properties. Series of fatigue tests in air at room temperature carried out in the low cycle fatigue range show a significant improvement of the fatigue life. The results are discussed especially taking into account the compressive residual stresses induced by the nitrided layer. Keywords: 316L
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Submitted on : Monday, June 14, 2010 - 3:06:33 PM
Last modification on : Tuesday, June 4, 2019 - 6:21:44 PM
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Jean-Charles Stinville. Evolution des microstructures et textures locales par nitruration plasma de l'acier 316L. Répercussion sur sa durabilité en fatigue. Sciences de l'ingénieur [physics]. ISAE-ENSMA Ecole Nationale Supérieure de Mécanique et d'Aérotechique - Poitiers, 2010. Français. ⟨tel-00491846⟩

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