D. Maisonnette, D. Nelias, INSA Lyon, Villeurbanne, France; M. Suery, INPG Grenoble, Saint-Martin d’Hères, France
The study deals with the mechanical behavior of a part made of 6061 aluminum alloy which is subjected during its manufacturing to various processes involving high temperatures such as solution treatment, aging, forging and welding. The final goal of this study is to optimize and predict the mechanical properties of the part in terms of yield stress, strain hardening behavior and ultimate tensile strength. These mechanical properties are strongly linked to the population of Mg2Si precipitates present in this age hardening aluminum alloy. The precipitate population is defined by the number and size of the precipitates.
For this optimization, it is necessary to link the precipitation state due to the thermal history, to the mechanical properties. The first step consists in performing controlled heat treatments and then associated analyses of the precipitate population. A typical thermal history is the one experienced by the volume near a welded joint (HAZ).
High heating rates up to 500 K/s, are obtained by Joule effect, also used to monitor a given thermal history. Characterization of the precipitation state is carried out by small angle neutron scattering (SANS). This method provides a good contrast between the matrix and the precipitates, and leads to accurate measurements compared to other methods such as small angle X-ray scattering (SAXS) for example. The obtained results are combined to TEM measurements in order to have good descriptions of the precipitate population. The mechanical properties are determined thanks to a tension-compression/torsion testing machine.
The methodology, the experimental set-up and the first results will be presented and discussed.
Summary: The 6061 Al precipitation state due to the thermal history is linked to the mechanical properties. Controlled heat treatments have been performed, and the subsequent precipitate population analyzed. A typical thermal history is the one experienced by the volume near a welded joint (HAZ). High heating rates up to 500 K/s, are obtained by Joule effect, also used to monitor a given thermal history. Characterization of the precipitation state is carried out by small angle neutron scattering (SANS). The obtained results are combined to TEM measurements in order to describe the precipitate population. The mechanical properties are determined thanks to a tension-compression/torsion testing machine.
