Modeling of the influence of coarsening on viscoplastic behavior of a 319 foundry aluminum alloy

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 559; pp. 40 - 48
• Main Authors: Martinez, R., Russier, V., Couzinié, J.P., Guillot, I., Cailletaud, G.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.01.2013; Elsevier
• Subjects: 319 Foundry aluminum alloy; Al2Cu coarsening; Applied sciences; Cross-disciplinary physics: materials science; rheology; Elasticity. Plasticity; Engineering Sciences; Exact sciences and technology; Fatigue; Low cycle fatigue behavior; Materials; Materials science; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Multiscale modeling; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Precipitation; Transmission electron microscope; Yield stress; Al2Cu coarsening; Low cycle fatigue behavior; 319 Foundry aluminum alloy; Yield stress; Multiscale modeling; Transmission electron microscope; Representative volume element; Orowan mechanism; Aluminium base alloys; Peierls stress; Ageing; Al; Elastoviscoplasticity; Solid solution; Cu coarsening; Low cycle fatigue; Cast alloy; Micromechanics; Time dependence; Precipitation; Multiscale method; Viscoplasticity; Yield strength; Microstructure
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2012.07.096

Both metallurgical and mechanical behaviors of a 319 foundry aluminum alloy have been modeled by means of a multiscale approach. The nano-scale, represented by the coarsening of Al2Cu precipitates, has been modeled according to the Lifshitz–Slyozov–Wagner (LSW) law in a range of temperature going from 23°C to 300°C up to 1000h aging time. Results were then compared to transmission electron microscope (TEM) observations and are in good agreement with the experimental measurements. The model allows us to know the critical radius, the volume fraction and the number of particles per μm3 in a α-phase representative volume element (RVE). The increase in yield stress generated by the interaction of dislocations with precipitates, lattice and solid solution, is modeled on the microscale. The yield stress becomes thus a function of the precipitation state, and is time/temperature dependent. These two models were then combined into a mechanical macroscale model in order to represent the Low Cycle Fatigue (LCF) behavior of the material. An elasto-viscoplastic law has been used and all the material parameters were experimentally determined with LCF stress/strain loops for the first cycle and for the mechanical steady state. The simulation results are in good agreement with the experiments.