The deformation response of L-grade stainless steels relative to IGSCC in 288 C water
- General Electric Corporate Research and Development, Schenectady, NY (United States)
Laboratory testing of L-grade stainless steels in representative boiling water nuclear reactor (BWR) core environments has shown that the intergranular (IG) cracking behavior is sensitive to the composition, corrosion potential and cold work. The objective of this study is to explore the deformation response of L-grade stainless steels to better understand its role on the IGSCC behavior. The deformation response was studied as a function of composition to evaluate the phase stability, susceptibility to sensitization and creep relaxation behaviors. The effect of deformation on 304, 304L, 316L and 316NG materials were evaluated metallographically and as a function of thermal treatment using the double loop electrochemical potentiokinetic reactivation (DL-EPR) technique. Metallographic results show that 304L is most likely to form deformation induced martensite, consistent with calculations. The DL-EPR response of 304L and 316L/NG materials increases significantly upon thermal treatment of cold worked material. These results are being used to determine the combinations of cold work and thermal treatment that promote IGSCC in 288 C high purity water at {approximately} +200mV{sub SHE} of 304L weld material obtained from an unirradiated nuclear station core shroud. The creep relaxation response of 304, 304L, 316L and 316NG materials were evaluated as a function of the stress intensity in 288 C air using compact tension specimens. The preliminary results suggest that the lower alloyed 304L exhibits more creep strain in the same period of time than higher alloyed 316L/NG and Alloy 600 materials. These results have implications in terms of the slip-oxidation model for crack advance where higher creep rates are expected to promote a higher crack tip strain rate and faster crack growth rates. Future work will study the crack growth rates of 304W316L/316NG in various states of cold work and thermal treatment to evaluate the roles of phase stability, sensitization and creep relaxation on the cracking susceptibility.
- OSTI ID:
- 350094
- Report Number(s):
- CONF-980316--
- Country of Publication:
- United States
- Language:
- English
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