Radiation hardening and radiation-induced chromium depletion effects on intergranular stress corrosion cracking in austenitic stainless steels. [Neutron radiation]
- Pacific Northwest Lab., Richland, WA (United States)
Radiation hardening and radiation-induced chromium (Cr) depletion were related to intergranular stress corrosion cracking (IGSCC) response among various stainless steels (SS). Available data on neutron-irradiated materials were analyzed and correlations developed between fluence, yield strength, grain-boundary Cr concentration, and cracking susceptibility in high-temperature water environments. Large heat-to-heat differences in the critical fluence (0.2 neutrons/cm[sup 2] to 2.5 [times] 10[sup 21] neutrons/cm[sup 2]) for IGSCC were documented. Variability often was consistent with yield strength differences among irradiated materials. IGSCC correlated better to yield strength than to fluence for most heats, suggesting a possible role for radiation-induced hardening (and microstructure) on cracking. However, isolated heats revealed a wide range of yield strengths (450 MPa to 800 MPa) necessary to promote IGSCC which could not be explained by strength effects alone. Grain-boundary Cr depletion qualitatively explained differences in IGSCC susceptibility for irradiated SS. Examination of measured Cr content vs SCC showed that all materials showing IG cracking had some grain-boundary depletion ([ge]2%). Grain-boundary Cr concentrations for cracking (< [approximately]16 wt%) were in good agreement with results from similar SCC tests on unirradiated type 304 SS (UNS S30400) with controlled depletion profiles. Heats that prompted variability in the yield strength correlation were accounted for by differences in their interfacial Cr contents. Thus, certain SS apparently were more resistant to cracking, even though they had significant radiation-induced Cr depletion. Cr depletion was believed to be required for SCC of irradiated SS, but susceptibility in this study was modified by other microchemical and microstructural components.
- OSTI ID:
- 6656566
- Journal Information:
- Corrosion (Houston); (United States), Journal Name: Corrosion (Houston); (United States) Vol. 50:12; ISSN 0010-9312; ISSN CORRAK
- Country of Publication:
- United States
- Language:
- English
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Radiation hardening and radiation-induced chromium depletion effects on intergranular stress corrosion cracking of austenitic stainless steels
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36 MATERIALS SCIENCE
360100* -- Metals & Alloys
ALLOYS
AUSTENITIC STEELS
CHEMICAL REACTIONS
CHROMIUM
CORROSION
CRACK PROPAGATION
ELEMENTS
GRAIN BOUNDARIES
HARDENING
INTERGRANULAR CORROSION
IRON ALLOYS
IRON BASE ALLOYS
LOSSES
MATERIALS
MECHANICAL PROPERTIES
METALS
MICROSTRUCTURE
PHYSICAL RADIATION EFFECTS
RADIATION EFFECTS
RADIATION HARDENING
REACTOR COMPONENTS
REACTOR CORES
REACTOR MATERIALS
REACTORS
STEELS
STRESS CORROSION
TRANSITION ELEMENTS
WATER COOLED REACTORS