The crystallography of fatigue crack initiation in Incoloy-908 and A-286 steel
- Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering
Fatigue crack initiation in the austenitic Fe-Ni superalloys Incoloy-908 and A-286 is examined using local crystallographic orientation measurements. Results are consistent with sharp transgranular initiation and propagation occurring almost exclusively on {l_brace}111{r_brace} planes in Incoloy-908 but on a variety of low index planes in A-286. This difference is attributed to the influence of the semicoherent grain boundary {eta} phase in A-286. Initiation in each alloy occurred both intergranularly and transgranularly and was often associated with blocky surface oxide and carbide inclusions. Taylor factor and resolved shear stress and strain crack initiation hypotheses were tested, but despite an inconclusive suggestion of a minimum required {l_brace}111{r_brace} shear stress, none of the hypotheses were found to convincingly describe preferred initiation sites, even within the subsets of transgranular cracks apparently free from the influence of surface inclusions. Subsurface inclusions are thought to play a significant role in crack initiation. These materials have applications for use in structural conduit for high field superconducting magnets designed for fusion energy use.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 459444
- Report Number(s):
- LBNL-39720; ON: DE97004173; TRN: 97:007845
- Resource Relation:
- Other Information: TH: Thesis (M.S.); PBD: Dec 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Caustic stress corrosion cracking of Inconel-600, Incoloy-800, and Type 304 stainless steel
Initiation and growth of small fatigue cracks in a Ni-base superalloy