Near-Surface Residual Stress Assessment in Inhomogeneous Nickel-Base Superalloys
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, Ohio 45221-0070 (United States)
Recently, it has been shown that shot-peened nickel-base superalloys exhibit an approximately 1% increase in apparent eddy current conductivity at high inspection frequencies, which can be exploited for nondestructive subsurface residual stress assessment. Unfortunately, microstructural inhomogeneity in certain as-forged and precipitation hardened nickel-base superalloys, like Waspaloy, can lead to significantly larger electrical conductivity variations of as much as 4-6%. This intrinsic conductivity variation adversely affects the accuracy of residual stress evaluation in shot-peened and subsequently thermal-relaxed specimens, but does not completely prevent it. Experimental results are presented to demonstrate that the conductivity variation resulting from volumetric inhomogeneities in as-forged engine alloys do not display significant frequency dependence. This characteristic independence of frequency can be exploited to distinguish these inhomogeneities from near-surface residual stress and cold work effects caused by surface treatment, which, in contrast, are strongly frequency-dependent.
- OSTI ID:
- 20798233
- Journal Information:
- AIP Conference Proceedings, Vol. 820, Issue 1; Conference: Conference on review of progress in quantitative nondestructive evaluation, Brunswick, ME (United States), 31 Jul - 5 Aug 2005; Other Information: DOI: 10.1063/1.2184689; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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