Microstructural evaluation of cumulative fatigue damage in a plant component sample
- Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo (Japan)
- Electric Power Research Inst., Charlotte, NC (United States). Nuclear Power Group
Fatigue damage accumulated in a real plant was evaluated in terms of microstructural conditioning. Microstructural damage induced in laboratory by cyclic deformation near and below the fatigue limit was also examined. A Transmission Electron Microscopy (TEM) technique called the Selected Area Diffraction (SAD) method was employed in this study. In earlier studies, it was found that the SAD value indicating a magnitude of crystallographic misorientation in the substructure (dislocation cells) was increasing with the increase of fatigue damage accumulation. Small samples removed from PWR feed water nozzle welds were examined by the SAD. It was found that the damage state measured by the SAD well agreed with the morphological evidence. Cyclic stresses near or below the fatigue limit were applied to samples taken from a SA508 steel plate at various stresses. The SAD value increased even below the fatigue limit, but there was no sign of microstructural conditioning below the stresses of 50% of the fatigue limit. These results suggested that at stresses below the current design curve (below half the fatigue limit) no microstructural conditioning proceeded. It was concluded that the microstructural method was effective to evaluate damage accumulation in real plant components, and also that the current design curve was adequate in terms of microstructural conditioning state.
- OSTI ID:
- 418103
- Report Number(s):
- CONF-960706-; ISBN 0-7918-1779-2; TRN: 97:001981
- Resource Relation:
- Conference: American Society of Mechanical Engineers (ASME) pressure vessels and piping conference, Montreal (Canada), 21-26 Jul 1996; Other Information: PBD: 1996; Related Information: Is Part Of Plant systems/components aging management -- 1996. PVP-Volume 332; Kisisel, I.T. [ed.] [Sargent and Lundy, Chicago, IL (United States)]; Peterson, D. [ed.] [Syncrude Canada Ltd., Edmonton, Alberta (Canada)]; Sinnappan, J. [ed.]; PB: 160 p.
- Country of Publication:
- United States
- Language:
- English
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