Investigation of the sulfur and lithium to sulfur ratio threshold in stress corrosion cracking of sensitized alloy 600 in borated thiosulfate solution
The stress corrosion cracking of sensitized Alloy 600 was investigated in aerated solutions of sodium thiosulfate generally containing 1.3% boric acid. The aim of the investigation, among others, was to determine the existence, if any, of a threshold level of sulfur, and lithium to sulfur ratio governing the SCC. Specimens were first solution annealed at 1135/sup 0/C for 45 minutes, water quenched, and then sensitized at 621/sup 0/C for 18 hours. Reverse U-bends were tested at room temperature, whereas slow strain rate and constant load tests were performed at 80/sup 0/C. All tests were performed in solutions open to the atmosphere. The results indicate that in the borated thiosulfate solution containing 7 ppM sulfur, 5 ppM lithium as lithium hydroxide is sufficient to inhibit SCC in U-bends. The occurrence of inhibition seems to correlate to the rapid increase of pH and conductivity of the solution as a result of the lithium hydroxide addition. In the slow strain rate tests in the borated solution containing 0.7 ppM lithium as lithium hydroxide, significant stress corrosion cracking is observed at a sulfur level of 30 ppb, i.e., a lithium to sulfur ratio of 23. In a parallel test in 30 ppb sulfur level but without any lithium hydroxide, the stress corrosion cracking is more severe than that in the lithiated environment, thus implying that lithium hydroxide plays some role in the stress corrosion cracking inhibition.
- Research Organization:
- Brookhaven National Lab., Upton, NY (USA)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 6932038
- Report Number(s):
- NUREG/CR-3834; BNL-NUREG-51785; ON: TI84015596
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
INCONEL 600
STRESS CORROSION
PWR TYPE REACTORS
REACTOR MATERIALS
STEAM GENERATORS
TUBES
BORIC ACID
CHEMICAL COMPOSITION
CRACK PROPAGATION
CRACKS
EXPERIMENTAL DATA
LITHIUM HYDROXIDES
WATER CHEMISTRY
ALKALI METAL COMPOUNDS
ALLOYS
BOILERS
CHEMICAL REACTIONS
CHEMISTRY
CHROMIUM ALLOYS
CORROSION
DATA
HYDROGEN COMPOUNDS
HYDROXIDES
INCONEL ALLOYS
INFORMATION
INORGANIC ACIDS
IRON ALLOYS
LITHIUM COMPOUNDS
MATERIALS
NICKEL ALLOYS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
NUMERICAL DATA
OXYGEN COMPOUNDS
REACTORS
VAPOR GENERATORS
WATER COOLED REACTORS
WATER MODERATED REACTORS
210200* - Power Reactors
Nonbreeding
Light-Water Moderated
Nonboiling Water Cooled
360105 - Metals & Alloys- Corrosion & Erosion