Berlin 2005 – scientific programme

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M: Metallphysik

M 39: Mechanische Eigenschaften II

M 39.3: Talk

Tuesday, March 8, 2005, 12:00–12:15, TU H111

Dynamic Recrystallization under Transient Deformation Conditions — •Matthias Frommert and Günter Gottstein — Institut für Metallkunde und Metallphysik, RWTH Aachen, D-52056 Aachen, Germany

Dynamic recrystallization (DRX) is a softening process that occurs during high temperature deformation and, therefore, affects the strength of a material. Dependent on the deformation parameters and initial grain size the typical DRX flow curve is known to display either a single-peak or multiple-peak behaviour before attaining steady-state stress. Transient deformation conditions such as changes of strain rate or temperature not only influence the shape of the flow curve but also the dynamically recrystallized grain size which is dependent on the steady-state flow stress.

Compression tests were performed with an austenitic steel Alloy 800H to investigate the mechanisms of DRX. Microstructure and texture were analysed using optical microscopy, SEM and X-ray diffraction, respectively. When the true strain rate is changed at a defined strain during the experiment the dynamically recrystallized grain size readjusts within a short strain interval as evident from the resulting change of steady-state flow stress. The inverse pole-figures demonstrate that during the early stages of high temperature deformation a typical deformation texture evolves which is randomized by the onset of DRX.