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MM: Fachverband Metall- und Materialphysik

MM 62: Topical session: X-ray and neutron scattering in materials science IV - High Energy Single Grain Diffraction

MM 62.2: Talk

Thursday, April 3, 2014, 18:00–18:15, BAR 205

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

Thermo-mechanical treatments of engineering metallic materials yield non-equilibrium microstructures, which influence important mechanical properties. An example is friction stir welding as a solid state joining process. Occurring non-equilibrium phases potentially reduce strength and toughness of a joint 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 material science beamline (HEMS) at DESY. Additionally, the phase transformations occurring in the steels used for friction stir welding were studied using a dilatometer in the synchrotron beam. With a fast area detector, time-resolved measurements with image rates up to 10 Hz were possible for both setups. The results on the phase content as a function of time obtained from the diffraction data in combination with the dilatometer signal improves the understanding of the processes occurring during friction stir welding of the investigated steels.