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MM: Fachverband Metall- und Materialphysik

MM 25: Microstructure and Phase Transformations III

MM 25.5: Vortrag

Dienstag, 27. März 2012, 12:45–13:00, H 0106

In situ investigation of phase transitions in friction stir welded steels using high-energy X-ray diffraction — •Malte Blankenburg, Peter Staron, Andreas Stark, Torben Fischer, Jakob Hilgert, Luciano Bergmann, Jorge F. dos Santos, Martin Müller, and Andreas Schreyer — Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Max-Planck-Strasse 1, 21502 Geesthacht, Germany

When engineering metallic materials are joined by friction stir welding, thermo-mechanical processes alter the base metal microstructure and properties. This induces the formation of non-equilibrium microstructures in the joint region, which are significantly different from those found in the base material. Such non-equilibrium microstructures can reduce strength and toughness of the material and are thus important to be studied. The intermediate stages of phase transformations in steels during the joining process can only be registered by in situ experiments. Therefore, in situ diffraction measurements using a transportable friction stir welding system (‘FlexiStir’) were performed at the HZG high-energy synchrotron beamlines HEMS and HARWI II at DESY. Additionally, the phase transformations occurring in the steels used for friction stir welding were studied using a dilatometer in the synchrotron beam. As a result, time resolved volume fractions of the steel phases during the phase transitions occurring during friction stir welding in different steels were obtained.