Journal
INTERNATIONAL JOURNAL OF PLASTICITY
Volume 27, Issue 5, Pages 801-821Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijplas.2010.09.009
Keywords
Fatigue; Grain boundaries; Polycrystalline material; Energy methods; Persistent slip bands
Funding
- Rolls-Royce Corporation
- National Science Foundation [DMR 08-03270]
- Direct For Mathematical & Physical Scien
- Division Of Materials Research [0803270] Funding Source: National Science Foundation
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In this paper, we construct a model for prediction of fatigue crack initiation based on the material's microstructure. In order to do so, the energy of a persistent slip band (PSB) is monitored and an energy balance approach is taken, in which cracks initiate and the material fails due to stress concentration from a PSB (with respect to dislocation motion). These PSBs are able to traverse low-angle grain boundaries (GB), thus belonging to clusters of grains. As a consequence of the ongoing cyclic slip process, the PSBs evolve and interact with high-angle GBs, the result of which leads to dislocation pile-ups, static extrusions in the form of ledges/steps at the GB, stress concentration, and ultimately crack initiation. Hence, this fatigue model is driven by the microstructure, i.e. grain orientations, widely distributed grain sizes, precipitates. PSB-GB interactions, as well as the affect of neighboring grains. The results predict that cracks initiate near twin boundaries from PSBs spanning a single large grain with a favorable orientation or multiple grains connected by low-angle GBs. Excellent agreement is shown between model predictions and experimental data. (C) 2010 Elsevier Ltd. All rights reserved.
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