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Title: Radiation hardening and radiation-induced chromium depletion effects on intergranular stress corrosion cracking of austenitic stainless steels

Conference ·
OSTI ID:6787431

Available data on neutron-irradiated materials have been analyzed and correlations developed between fluence, yield strength, grain boundary chromium concentration and cracking susceptibility in high-temperature water environments. Large heat-to-heat differences in critical fluence (0.2 to 2.5 n/cm[sup 2]) for IGSCC are documented.In many cases, this variability is consistent with yield strength differences among irradiated materials. IGSCC correlated better to yield strength than to fluence for most heats suggesting a possible role of the radiation-induced hardening (and microstructure) on cracking. However, isolatedheats reveal a wide range of yield strengths from 450 to 800 MPa necessary to promote IGSCC which cannot be understood by strength effects alone. Grain boundary Cr depletion explain differences in IGSCC susceptibility for irradiated stainless steels. Cr contents versus SCC shows that all materials showing IG cracking have some grain boundary depletion ([ge]2%). Grain boundary Cr concentrations for cracking (below [approximately]16 wt %) are in good agreement with similar SCC tests on unirradiated 304 SS with controlled depletion profiles. Heats that prompt variability in the yield strength correlation, are accounted for bydifferences in their interfacial Cr contents. Certain stainless steels are more resistant to cracking even though they have significant radiation-induced Cr depletion. It is proposed that Cr depletion is required for IASCC, but observed susceptibility is modified by other microchemical and microstructural components.

Research Organization:
Pacific Northwest Lab., Richland, WA (United States)
Sponsoring Organization:
USDOE; USDOE, Washington, DC (United States)
DOE Contract Number:
AC06-76RL01830
OSTI ID:
6787431
Report Number(s):
PNL-SA-21491; CONF-930318-9; ON: DE93011602
Resource Relation:
Conference: NACE annual corrosion conference and materials performance and corrosion show, New Orleans, LA (United States), 7-12 Mar 1993
Country of Publication:
United States
Language:
English