The effects of nitrate on the stress corrosion cracking of sensitized stainless steel in high temperature water
- GE Corporate Research and Development Center, Schenectady, NY (United States)
The effects of nitrate additions as HNO{sub 3} and NaNO{sub 3} on the stress corrosion crack growth rate of 1TCT specimens of sensitized type 304 stainless steel were studied in 270 and 288 C water using the reversing dc potential drop technique. Most studies were limited to 100 ppb nitrate, although concentrations as high as 10 ppm were also used. No significant effect on crack growth rate was observed at {<=}100 ppb, although large increases were observed at 10 ppm. Some earlier studies had shown an increase in crack growth rate at {<=} 100 ppb nitrate, although they were probably influenced by variations in the corrosion potential. In contrast to some other species, nitrate is efficiently reduced in the crack to ammonia, a species that causes alkalinization, not acidification. The increase in crack growth rate at very high nitrate levels is consistent with data obtained in NAOH, and shows that elevated crack growth rates are possible in sufficiently alkaline solutions. In aerated water, the reduction of nitrate occurs only when nitrate migrates into the crack, since in high temperature water the crack is deaerated and at low potential. NWIE not evaluated, materials such as nonsensitized or irradiated stainless steel, nickel alloys, and carbon and low alloy steels should exhibit a similar insensitivity to nitrate.
- OSTI ID:
- 203837
- Report Number(s):
- CONF-950816-; ISBN 1-877914-95-9; TRN: 96:009803
- Resource Relation:
- Conference: 7. international symposium on environmental degradation of materials in nuclear power plants: water reactors, Breckenridge, CO (United States), 6-10 Aug 1995; Other Information: PBD: 1995; Related Information: Is Part Of Seventh international symposium on environmental degradation of materials in nuclear power systems -- Water reactors: Proceedings and symposium discussions. Volume 1; Airey, G.; Andresen, P.; Brown, J. [eds.] [and others]; PB: 664 p.
- Country of Publication:
- United States
- Language:
- English
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