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Modélisation numérique du grenaillage des pièces initialement cémentées ou carbonitrurées

Abstract : Surface treatments are increasingly used to enhance fatigue resistance of metallic parts by improving material properties. At PSA Peugeot Citroen Company, some parts are treated thermo-chemically (by carburizing or carbonitriding) before shot-peening, in order to benefit from the advantages of each treatment. The aim of this study is to understand the combination of the effect of thermochemical treatments and of shot peening on the generation of residual mechanical fields. Experimental investigations have highlighted the following effects of shot-peening on a carburized (or carbonitrided) material in the surface layer: (a) shot-peening increases the hardness, (b) it increases considerably the level of residual stresses, (c) it makes it possible to transform residual austenite into martensite. This study deals with a finite element model of shot peening after thermochemical treatments. Mechanical state resulting from thermo-chemical processes are implemented in the model from experimental data obtained by X-ray diffraction stress analyses. Consequently, the shot-peening numerical simulation takes into account this initial state in terms of residual stresses, plastic strains and hardening parameters. Besides, the material exhibits a gradient of microstructure and mechanical properties due to the thermochemical treatment. Thus, it is modeled as a composite material, where the gradient of mechanical properties (stress-strain curve at a given depth) is linked to the in-depth measured hardness. This model is used to estimate the residual stress and plastic strain gradient following the shot peening process of an already thermochemically treated component.
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Contributor : Pierre Renaud <>
Submitted on : Wednesday, July 6, 2011 - 1:42:00 AM
Last modification on : Wednesday, November 29, 2017 - 9:42:51 AM
Long-term archiving on: : Friday, October 7, 2011 - 2:20:31 AM

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Pierre Renaud. Modélisation numérique du grenaillage des pièces initialement cémentées ou carbonitrurées. Mécanique des matériaux [physics.class-ph]. Ecole nationale supérieure d'arts et métiers - ENSAM, 2011. Français. ⟨NNT : 2011ENAM0018⟩. ⟨pastel-00606275⟩

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