Creep and Environmental Effects on High Temperature Creep-Fatigue Behavior of Alloy 617
Alloy 617 is the leading candidate material for Intermediate Heat Exchanger (IHX) of a Very High Temperature Reactor (VHTR), expected to have an outlet temperature as high as 950 C. System start-ups and shut-downs as well as power transients will produce low cycle fatigue (LCF) loadings of components. Acceptance of Alloy 617 in Section III of the ASME Code for nuclear construction requires a detailed understanding of the creep-fatigue behavior in both air and impure helium, representative of the VHTR primary coolant. Strain controlled LCF tests including hold times at maximum tensile strain were conducted at total strain range of 0.3% in air at 950 C. Creep-fatigue testing was also performed in a simulated VHTR impure helium coolant for selected experimental conditions. The fatigue resistance decreased when a hold time was added at peak tensile stress, consistent with the observed change in fracture mode from transgranular to intergranular with introduction of a tensile hold. Increases in the tensile hold time, beyond 180 sec, was not detrimental to the creep-fatigue resistance. Grain boundary damage in the form of grain boundary cracking was present in the bulk of the creep-fatigue specimens. This bulk cracking was quantified and found to be similar for hold times of up to 1800 sec consistent with the saturation in failure lives and rapid stress relaxation observed during the creep portion of the creep-fatigue cycle.
- Research Organization:
- Idaho National Lab. (INL), Idaho Falls, ID (United States)
- Sponsoring Organization:
- DOE - NE
- DOE Contract Number:
- DE-AC07-05ID14517
- OSTI ID:
- 1028225
- Report Number(s):
- INL/JOU-11-20890; TRN: US1105555
- Journal Information:
- Journal of ASTM International, Vol. 8, Issue 6
- Country of Publication:
- United States
- Language:
- English
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Creep-Fatigue Behavior of Alloy 617 at 850°C
Low Cycle Fatigue and Creep-Fatigue Behavior of Alloy 617 at High Temperature
Related Subjects
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
AIR
ALLOYS
CRACKING
CREEP
FAILURES
FATIGUE
FRACTURES
HEAT EXCHANGERS
HELIUM
INCONEL 617
VHTR REACTOR
REACTOR COMPONENTS
STRAINS
STRESS RELAXATION
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
TESTING
TRANSIENTS
Alloy 617
creep-fatigue
creep-fatigue interaction
environment
helium
nickel alloy