Please use this identifier to cite or link to this item: doi:10.22028/D291-32155
Title: Acquiring in situ Fatigue Crack Growth Curves by a Compliance Method for Micro Bending Beams to Reveal the Interaction of Fatigue Cracks with Grain Boundaries
Author(s): Gruenewald, Patrick
Rauber, Jonas
Marx, Michael
Motz, Christian
Schäfer, Florian
Language: English
Title: Procedia Structural Integrity
Pages: 13-20
Publisher/Platform: Elsevier
Year of Publication: 2019
Title of the Conference: ICSI 2019 The 3rd International Conference on Structural Integrity
Free key words: small fatigue cracks
dislocation grain boundary interaction
micro bending beam
compliance method
micro specimen
DDC notations: 500 Science
530 Physics
540 Chemistry
620 Engineering and machine engineering
621.3 Electrical engineering, electronics
Publikation type: Conference Paper
Abstract: To understand the interaction of dislocations with microstructural obstacles it is necessary to find test methods which are able to resolve the interaction of only a single or few defects with obstacles like interfaces. Therefore, the investigation of micro specimens has been established over the years as a suitable method to test the influence of microstructural features on the mechanical response. While quasi-static loading of micro specimens has been carried out extensively in the past decade and has given powerful insights on the mechanical behavior at small scales, cyclic loading and fatigue crack growth experiments still provide a challenge. In order to check the possibility to systematically initiate and monitor fatigue crack growth rates in micro specimens, we cyclically loaded micro bending beams made of a nickelbase superalloy. Furthermore, for grain boundaries of differing types we checked if the crack growth curves are suitable to measure crack - microstructure interactions. The fatigue cracks showed a deceleration when approaching the grain boundaries followed by an abrupt re-acceleration, which is in accordance to macroscopic experiments and connected to dislocation or slip transfer from the plastic zone of the crack through the grain boundary. Furthermore, we observed a dependency of the deceleration on the grain boundary type and the crystallographic orientation of the neighboring grains. A 3D-HR-orientation gradient map was gathered by HR-EBSD using the software CrossCourt in combination with a self-provided MATLAB tool to reveal detailed information about strain localization at the grain boundary in the process zone near the crack tip.
DOI of the first publication: 10.1016/j.prostr.2019.08.003
Link to this record: urn:nbn:de:bsz:291--ds-321553
Date of registration: 14-Sep-2020
Notes: Procedia Structural Integrity, 17 (2019), S. 13-20
Faculty: NT - Naturwissenschaftlich- Technische Fakultät
Department: NT - Materialwissenschaft und Werkstofftechnik
Professorship: NT - Prof. Dr. Christian Motz
Collections:SciDok - Der Wissenschaftsserver der Universität des Saarlandes

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