Fracture toughness assessment of in-service aged primary circuit elbows using mini C(T) specimens taken from outer skin
- EDF-Centre de Renardieres, Moret-sur-Loing (France). Dept. of Materials Study
- Framatome, Paris-la-Defense (France). Dept. of Materials and Technology
- EDF, Chinon (France)
Type CF8M cast duplex stainless steels used in the primary circuit elbows of pressurized water reactors are subject to thermal aging embrittlement at their service temperature, around 300 C. This phenomenon affects their fracture toughness properties. In order to assess the residual fracture toughness of these elbows, estimations are made through predictive formulae based on chemical composition and aging conditions, which provide safe values. However, in the case of the most sensitive materials, it is important to obtain more accurate estimations. A new method of determination was thus considered, based on the testing of mini-CT specimens taken from the skin of in-service elbows. The feasibility of using mini-CT specimens to evaluate the tearing resistance of cast duplex stainless steels seems at first sight difficult, in particular because of the very coarse metallurgical structure of these steels: will small specimens be representative of larger volumes (mainly regular IT-CT specimens) and will they not induce too much scatter? In order to answer such questions, an experimental validation program has been undertaken: the completed program shows that the method is relevant and leads to proposed guidelines which aim at optimizing the experimental results analysis. Then the method is applied to an in-service elbow: the results obtained are found to be in good agreement with the toughness estimations given by the predictive formulae. This subsequently contributes to the validation of the general methodology used for the justification of French primary circuit elbows.
- OSTI ID:
- 122605
- Report Number(s):
- CONF-950740-; ISBN 0-7918-1335-5; TRN: 95:024231
- Resource Relation:
- Conference: Joint American Society of Mechanical Engineers (ASME)/Japan Society of Mechanical Engineers (JSME) pressure vessels and piping conference, Honolulu, HI (United States), 23-27 Jul 1995; Other Information: PBD: 1995; Related Information: Is Part Of Fatigue and fracture mechanics in pressure vessels and piping. PVP-Volume 304; Mehta, H.S.; Wilkowski, G.; Takezono, S.; Bloom, J.; Yoon, K.; Aoki, S.; Rahman, S.; Nakamura, T.; Brust, F.; Yoshimura, S. [eds.]; PB: 594 p.
- Country of Publication:
- United States
- Language:
- English
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