Microstructural statistics for fatigue crack initiation in polycrystalline nickel-base superalloys

• Published in: International journal of fracture Vol. 208; no. 1-2; pp. 221 - 240
• Main Authors: Stinville, J. C., Lenthe, W. C., Echlin, M. P., Callahan, P. G., Texier, D., Pollock, T. M.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-12-2017; Springer Nature B.V; Springer Verlag
• Subjects: Automotive Engineering; Characterization and Evaluation of Materials; Chemistry and Materials Science; Civil Engineering; Classical Mechanics; Crack initiation; Crack propagation; Criteria; Cyclic loads; Engineering Sciences; Fatigue cracks; Fatigue failure; Fracture mechanics; Grain size; Inclusions; IUTAM Baltimore; Materials; Materials Science; Mechanical Engineering; Mechanics; Mechanics of materials; Micro and nanotechnologies; Microelectronics; Microstructure; Nickel; Nickel base alloys; Parameter identification; Physics; Superalloys; Twin boundaries; Strain localization; Polycrystalline superalloys; Fatigue initiation volume element; Low cycle fatigue; High resolution digital image correlation; Fatigue initiation; Polycrystalline superalloys, Strain localization, Low; cycle fatigue, Fatigue initiation, High resolution; digital image correlation
• ISSN: 0376-9429; 1573-2673
• DOI: 10.1007/s10704-017-0241-z

In advanced engineering alloys where inclusions and pores are minimized during processing, the initiation of cracks due to cyclic loading shifts to intrinsic microstructural features. Criteria for the identification of crack initiation sites, defined using elastic-plastic loading parameters and twin boundary length, have been developed and applied to experimental datasets following cyclic loading. The criteria successfully quantify the incidence of experimentally observed cracks. Statistical microstructural volume elements are defined using a convergence approach for two nickel-base superalloys, IN100 and René 88DT. The material element that captures the fatigue crack-initiating features in René 88DT is smaller than IN100 due to a combination of smaller grain size and higher twin density.