Berlin 2015 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 13: Microstructure and Phase Transformations III

MM 13.3: Vortrag

Montag, 16. März 2015, 16:15–16:30, H 0106

In situ investigation of the microstructure in friction stir welded steels usind high-energy X-ray diffraction — •Malte Blankenburg, Peter Staron, Andreas Stark, Torben Fischer, Daniel Laipple, 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 potentially reduce strength and toughness of a joint. As a solid state joining process, friction stir welding reduces the heat input and increases the mechanical properties of the weld. The intermediate stages of phase transformations in the weld zone during the joining process can only be studied 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. With a fast area detector, time-resolved measurements with image rates up to 10 Hz were possible, delivering detailed insight to the time development of the ferrite and austenite content of small gauge volumes at different positions relative to the welding tool. Post-mortem EBSD analysis of weld profiles were performed to confirm the results of the in situ welding experiments. Additionally, the phase transformations in the steels used for friction stir welding were studied with a dilatometer (DIL805 A/D) in the synchrotron beam.