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Contribution a l'étude expérimentale et numérique du soudage laser : application aux alliages de magnésium

Abstract : This work deals with laser beam welding of AM60 magnesium alloy. It concerns experimental investigations and numerical simulations. The experimental study aims to investigate metallurgical and mechanical process consequences on studied alloy and to validate thermal model results. Firstly, a parametric study allows the determination of the CO2 laser beam welding parameters of plates with 3 mm thickness. Secondly, temperature evolution according time during welding are monitored using thermocouples fixed in the vicinity of the weld. Then, metallographic investigations are performed to reveal that the coarse grains of base metal are transformed into dendritic structure in the molten zone. Whereas, in the heat affected zone, a reduction in primary phase grain size is observed. Finally, mechanical characterisations show an increase in hardness in molten zone and a reduction in total elongation for the weld. But, strength properties are similar in the weld and base metal. The numerical study aims to predict thermal history and mechanical characteristics evolution of weldment during laser welding. Within the Finite Element (FE) code Cast3M, two three-dimensional nonstationary and nonlinear models are developed. The first allows the simulation of the space-time temperature distribution. In this case, the applied loading depends on process parameters and laser beam characteristics. It is associated to mobile boundary conditions. The thermal model results are in agreement with monitored temperature evolutions. In the second simulation, residual stresses and strains distributions are determined during welding. For the mechanical model, an elastoplastic behaviour with a transitory thermal loading is assumed, resulting from the thermal model. The nonlinear transitory analysis is able to predict stresses and strains evolutions according time as well as residual stress and strain distribution generated in the laser beam welded parts. The comparison of the residual stresses simulated profile with results from the literature enables a qualitative validation of the mechanical model
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https://pastel.archives-ouvertes.fr/pastel-00004942
Contributor : Ecole Arts Et Métiers Paristech <>
Submitted on : Thursday, July 23, 2009 - 8:00:00 AM
Last modification on : Wednesday, November 29, 2017 - 9:42:49 AM
Long-term archiving on: : Thursday, September 30, 2010 - 9:00:13 PM

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  • HAL Id : pastel-00004942, version 1

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Asma Belhadj. Contribution a l'étude expérimentale et numérique du soudage laser : application aux alliages de magnésium. Sciences de l'ingénieur [physics]. Arts et Métiers ParisTech, 2009. Français. ⟨NNT : 2009ENAM0001⟩. ⟨pastel-00004942⟩

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