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Modelling precipitation hardening in an A356+0.5Cu cast aluminum alloy

Abstract : Aluminum alloys of type A356+0.5Cu are widely used in casting cylinder heads for automotive applications due to their good thermal and mechanical properties. The yield stress in these alloys is closely related to precipitation microstructure, the formation and evolution of which are diffusion controlled. In this work, the precipitation kinetics of the β”-Mg2Si hardening phase and the associated evolution of yield stress are modelled. Precipitation is modelled based on classical nucleation theory equations and diffusion controlled growth. The KWN size class discretization approach was used to track the evolution of size distributions of precipitates in response to a given thermal history. Yield stress was modelled by adding up the contributions of precipitates and solid solution strengthening in a manner directly informed by the precipitation model. The contribution of precipitates was modelled taking into account their rod morphology and their orientation in the matrix. Samples were cast and were subject to a solutionizing, quenching and aging heat treatment for various durations. The model was then confronted, on two levels, to the results of experiments conducted on these samples. On the one hand, simulated size distributions were compared to measurements performed on precipitates observed using electron transmission microscopy. On the other hand, the simulated yield stress was compared to the results of tensile tests. Finally, a finite-elements computation chain integrating these models was developed in the Z-Set framework. It was then used to simulate quenching and aging heat treatment making possible tracking of property gradients as well as estimating and localizing residual stresses.
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Submitted on : Tuesday, October 12, 2021 - 10:48:12 AM
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  • HAL Id : tel-03374503, version 1

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Anass Assadiki. Modelling precipitation hardening in an A356+0.5Cu cast aluminum alloy. Materials. Université Paris sciences et lettres, 2020. English. ⟨NNT : 2020UPSLM074⟩. ⟨tel-03374503⟩

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