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M: Metallphysik

M 27: Mechanische Eigenschaften IV

M 27.1: Vortrag

Donnerstag, 11. März 2004, 11:45–12:00, H4

Dynamic Recrystallization in Steady-State Regime — •Matthias Frommert and Günter Gottstein — Institut für Metallkunde und Metallphysik, RWTH Aachen, D-52056 Aachen

The typical flow curve of a material which undergoes dynamic recrystallization can be either described by a single-peak or a multiple-peak behaviour followed by a steady-state stress level at higher strains. Investigations on a large variety of materials have shown that the dynamically recrystallized grain size does not change in the steady-state regime and can be correlated to the steady-state flow stress. In the current study compression tests were performed with an austenitic steel Alloy 800H at constant and transient strain rates in order to investigate the physical mechanisms of steady-state dynamic recrystallization. Microstructure and microtexture were studied by optical microscopy and SEM. When the true strain rate is changed at a defined strain during experiment the dynamically recrystallized grain size readjusts within a short strain interval according to the resulting change of steady-state flow stress. The macrotexture was measured using X-ray diffraction; the inverse pole-figures show that during the early stages of high temperature deformation a typical deformation texture evolves which is randomized by the onset of dynamic recrystallization.