Precipitation and plasticity couplings in a 7xxx aluminium alloy: application to thermomechanical treatments for distortion correction of aerospace component

Abstract : 7xxx aluminium alloys are high strength alloys mainly used for aerospace applications due to their high specific mechanical properties. Manufacturing these age-hardenable alloys involves complex thermomechanical treatments that develop the precipitation microstructure responsible for the mechanical properties. Undesirable long-range internal stresses are also produced during these treatments, and may induce severe distortions in the final products. Different thermomechanical processes: shot peening, laser forming and age-forming (respectively a purely mechanical, a purely thermal and a thermomechanical treatment) are used to reduce internal stresses and/or part distortion in aerospace aluminium 7xxx machined components. However, they modify the material's microstructure and consequently the mechanical properties. We have examined the couplings between these thermomechanical treatments, the microstructure and the mechanical properties, throughout experimental characterization and physically based modelling. The effect of precipitation on the strain hardening properties is investigated, to establish a physically-based strain hardening model able to be used in a shot peening finite element model. Then, the effect of laser forming on the precipitation state and on the material strength is examined. The last part is dedicated to the study of the effect of age forming – a process combining simultaneous plastic deformation and heat treatment - on precipitation.
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Mechanics [physics.med-ph]. Institut National Polytechnique de Grenoble - INPG, 2009. English


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Submitted on : Thursday, July 15, 2010 - 11:28:40 AM
Last modification on : Thursday, July 15, 2010 - 11:32:18 AM

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Guillaume Fribourg. Precipitation and plasticity couplings in a 7xxx aluminium alloy: application to thermomechanical treatments for distortion correction of aerospace component. Mechanics [physics.med-ph]. Institut National Polytechnique de Grenoble - INPG, 2009. English. <tel-00502536>

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