MATEC Web Conf.
Volume 165, 201812th International Fatigue Congress (FATIGUE 2018)
|Number of page(s)||8|
|Section||Crack Initiation Process and First Stages of Crack Propagation|
|Published online||25 May 2018|
Effect of local anisotropy on fatigue crack initiation in a coarse grained nickel-base superalloy
Institute of Materials Science and Engineering, University of Kaiserslautern, Germany
2 Bergische Universität Wuppertal, Gaußstraße 20, 42119 Wuppertal, Germany
3 Siemens AG, Huttenstraße 12, 10553 Berlin, Germany
* Corresponding author: email@example.com
In the present work, theoretical approaches, based on grain orientation dependent Young’s modulus and Schmid factor are used to describe the influence of local grain orientation on crack initiation behaviour of the coarse grained nickel base superalloy René80. Especially for strongly anisotropic crystal structures with large grain size, such as the investigated material, the local elastic properties must be taken into account for assessment of fatigue crack initiation. With an extension of Schmid’s law, the resulting shear stress amplitude, which triggers local cyclic plastic deformation, can be calculated depending on local Young`s modulus and Schmid factor. A Monte Carlo simulation with 100,000 samples shows how random grain orientation affects these parameters. Furthermore, the product of Young`s modulus and Schmid factor (called E·m) is used as a parameter to determine how grain orientation influences resulting shear stress amplitude for given total strain amplitude. In addition to the theoretical work using that approach, this model is also validated using isothermal LCF experiments by determining local grain orientation influence on the crack initiation site using SEM-EBSD analyses.
© The Authors, published by EDP Sciences, 2018
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (http://creativecommons.org/licenses/by/4.0/).
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