Regensburg 2010 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 13: Topical Session Designing Innovative Structural Materials and Steels IV

MM 13.3: Talk

Monday, March 22, 2010, 16:30–16:45, H4

In-situ investigation of precipitation in AA7449 friction stir welds using high energy SAXS — •Torben Fischer, Peter Staron, Luciano Bergmann, Jorge F. dos Santos, and Andreas Schreyer — GKSS Research Centre, Institute of Materials Research, Max-Planck-Strasse 1, 21502 Geesthacht, Germany

Friction stir welding (FSW) has in a very short time found a multitude of applications for high-tech applications in the transportation and energy industries. When engineering metallic materials are friction stir welded, thermo-mechanical processes alter the base metal microstructure and properties. The result is the formation of non-equilibrium microstructures in the joint region, which are significantly different from those found in the base material. Such non-equilibrium phases can reduce strength and toughness of the material and are normally compensated by increasing the dimensions or design complexity of integral structures.

The intermediate stages of precipitation or phase transformations in the weld zone during welding can only be registered by in-situ experiments. Therefore, a new transportable FSW system 'FlexiStir', for in-situ measurements was developed by GKSS. The in-situ experiments with the FlexiStir took place at the GKSS high-energy synchrotron beamline HARWI II at HASYLAB. Small-angle X-ray scattering (SAXS) at high photon energies was used to obtain spatial resolved results on volume fractions and sizes of precipitates at different locations in the weld zone.