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S. Vincent, P. Lang, E. Kozeschnik et al.:
"Optimization of the fabrication process of 6061 aluminum alloys using experiments and thermokinetic simulations";
Poster: Calphad XLI, Berkley, USA; 2012-06-03 - 2012-06-08.

In 6xxx series aluminum alloy, Mg2Si phases are the stable phases resulting from the Al-Mg-Si precipitation sequence. In these industrial hardening alloys, two sizes Mg2Si precipitates coexist: intragranular nanometric and rough intergranular (~1µm) ones. In service conditions, the damage initialization is located on the rough Mg2Si precipitates. Thus, it is necessary to decrease the amount of these precipitates during fabrication process to improve the mechanical properties.
In this framework, two 6061 aluminum alloys are studied: the first one with a classical industrial composition (material A) and the second one containing reduced amounts of Mg and Si (material B). The fabrication process is investigated experimentally and reproduced by thermokinetic simulations using MatCalc software. It is divided into seven steps: casting, homogenization, forging, solutionizing plus quenching, release and tempering. In this work, we focused on the first steps of the process until forging. The calculations are compared with in-situ neutron diffraction experiments, phase fractions and mean radius measurements obtained by SEM.
Reduced amounts of rough Mg2Si precipitates are obtained on material B compared to material A, after fabrication process -these results are observed both experimentally and by MatCalc simulations.
Finally, the MatCalc script created within this work allows to test the influence of the variation of different parameters (chemical composition, time/temperature heat treatment, heating/cooling rate...) on the evolution of the rough Mg2Si precipitates at each step of the process.