Competing Modes for Crack Initiation from Non-metallic Inclusions and Intrinsic Microstructural Features During Fatigue in a Polycrystalline Nickel-Based Superalloy

Cyclic fatigue experiments in the high and very high cycle fatigue regimes have been performed on a René 88DT polycrystalline nickel-based superalloy. The microstructural configurations that favor early strain localization and fatigue crack initiation at high temperature from 400 °C to 650 °C have b...

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Published in:Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2018-09, Vol.49 (9), p.3865-3873
Main Authors: Stinville, Jean-Charles, Martin, Etienne, Karadge, Mallikarjun, Ismonov, Shak, Soare, Monica, Hanlon, Tim, Sundaram, Sairam, Echlin, McLean P., Callahan, Patrick G., Lenthe, William C., Miao, Jiashi, Wessman, Andrew E., Finlay, Rebecca, Loghin, Adrian, Marte, Judson, Pollock, Tresa M.
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Chemistry and Materials Science
Crack initiation
Crack propagation
Crystallography
Damage accumulation
Damage localization
Failure modes
Fatigue cracks
Fatigue failure
Fracture mechanics
High cycle fatigue
Localization
Materials Science
Metallic Materials
Nanotechnology
Nickel
Nickel base alloys
Nonmetallic inclusions
Polycrystals
Strain localization
Structural Materials
Superalloys
Surfaces and Interfaces
Thin Films
Third European Symposium on Superalloys and their Applications
Topical Collection: Superalloys and Their Applications
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Summary:Cyclic fatigue experiments in the high and very high cycle fatigue regimes have been performed on a René 88DT polycrystalline nickel-based superalloy. The microstructural configurations that favor early strain localization and fatigue crack initiation at high temperature from 400 °C to 650 °C have been investigated. Competing failure modes are observed in the high to the very high cycle fatigue regime. Fatigue cracks initiate from non-metallic inclusions and from intrinsic internal microstructural features. Interestingly, as stresses are reduced into the very high cycle regime, there is a transition to initiation only at crystallographic facets. At higher stress in the high cycle fatigue regime, a significant fraction of specimens initiate cracks at non-metallic inclusions. This transition is analyzed with regard to microstructural features that favor strain localization and accumulate damage early during cycling.
ISSN:1073-5623
1543-1940
DOI:10.1007/s11661-018-4780-3