Factors controlling hydrogen assisted subcritical crack growth in Zr--2. 5Nb alloys
Delayed failure of cold-worked Zr--2.5Nb pressure tube material was studied using static load tests on compact-tension specimens containing hydrogen within the range approx. 10 to 400 ..mu..g/g. The experimental approach was to measure crack velocity (V) as a function of crack tip stress intensity factor (K), temperature and hydrogen content, relate these data to fractographic and metallographic observations, and compare the results with recent models of hydrogen embrittlement. Slow crack growth was observed at all temperatures between 25 and 325/sup 0/C and at K values between approx. 10 and 50 MPa ..sqrt..m. Below 250/sup 0/C, the V--K relationships exhibited two-stage behavior; at K > 15 to 20 MPa ..sqrt..m, the crack velocity was only weakly dependent on stress intensity, whereas at smaller K values, the crack velocity decreased rapidly with K, an indication of a threshold value of K approx. 5 to 10 MPa ..sqrt..m. The crack velocity increased with increase in temperature: this general mode of crack growth was considered in a recent model for embrittlement in hydride-forming materials, the predictions of which show good agreement with the results from this study.
- Research Organization:
- Atomic Energy of Canada Limited, Pinawa, Manitoba
- OSTI ID:
- 6431093
- Journal Information:
- Am. Soc. Test. Mater., Spec. Tech. Publ.; (United States), Journal Name: Am. Soc. Test. Mater., Spec. Tech. Publ.; (United States) Vol. 633; ISSN ASTTA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
220300 -- Nuclear Reactor Technology-- Fuel Elements
36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
COLD WORKING
CRACKS
CRYOGENIC FLUIDS
DISTRIBUTION
ELEMENTS
FABRICATION
FAILURES
FATIGUE
FLUIDS
FRACTURES
FUEL CANS
HYDRIDES
HYDROGEN
HYDROGEN COMPOUNDS
MATERIALS WORKING
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
NIOBIUM ALLOYS
NONMETALS
PRECIPITATION
SEPARATION PROCESSES
TEMPERATURE DEPENDENCE
ZIRCONIUM ALLOYS
ZIRCONIUM BASE ALLOYS