Regensburg 2016 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 23: Mechanical Properties II

MM 23.4: Talk

Tuesday, March 8, 2016, 12:30–12:45, H52

Sequence of microstructure evolution processes in steel under tribological loading — •Christian Greiner, Karsten Wolff, Daniel Braun, Zhilong Liu, and Johannes Schneider — KIT, Kaiserstrasse 12, 76131 Karlsruhe

The exact evolution of a material's microstructure under tribological loading is of great importance for both materials physics and tribology. There is however a significant lack of knowledge about the elementary mechanisms of microstructure evolution under tribological load as well as their kinetics. Therefore, the microstructure evolution of steel C85 pellets sliding against steel 100Cr6 disks is characterized after different numbers of acceleration-deceleration cycles. Focused ion beam cross-sections are prepared along the sliding direction. Two tribologically modified surface layers are found: One with bent grain boundaries and one of nanocrystalline nature. We hypothesize that the second layer is formed by breaking down the most bent regions of the first one when a critical grain boundary bending angle is reached and then consumes it from the top. A model originally developed for High Pressure Torsion (HPT) was successfully applied to estimate the thickness of the fine-grained layer and the applied shear strain.