Environmental factors in the stress corrosion cracking of type 316L stainless steel and alloy 825 in chloride solutions
- Southwest Research Inst., San Antonio, TX (United States). Center for Nuclear Waste Regulatory Analyses
This paper describes the experimental studies conducted to date to investigate the stress corrosion cracking (SCC) of candidate container materials for the proposed high-level nuclear waste repository at Yucca Mountain, Nevada. The effects of environmental variables, such as chloride concentration, the addition of thiosulfate, and temperature on the SCC susceptibility of type 316L, stainless steel (SS) and alloy 825 (Ni-29% Fe-22% Cr-3.0% Mo-2.0% Cu-1.0% Ti) were studied at temperatures from 95 C to 120 C. Results of slow strain rate tests (SSRT) at various potentials were compared to those obtained under constant deflection conditions using U-bend specimens to determine the existence of a critical potential for SCC. While not conclusive, results generated thus far have been consistent with the hypothesis that the repassivation potential for localized corrosion is also the critical potential for SCC in these environments. It was confirmed that alloy 825 was significantly more resistant to SCC than type 316L SS, using both constant deflection tests and SSRT, over a wide range of Cl{sup {minus}} concentrations. In contrast deflection tests, type 316 L SS exhibited cracks above the vapor-solution interface in solutions containing 1,000 ppm Cl{sup {minus}}, indicating that the local environment created as a liquid film on the specimen surface could be more detrimental than the bulk environment. SCC of type 316L SS was observed in SSRT only at Cl{sup {minus}} concentrations > {approximately}6 molal, whereas U-bend tests indicated cracking in 0.03 molal Cl{sup {minus}} solutions.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 215644
- Journal Information:
- Corrosion, Journal Name: Corrosion Journal Issue: 3 Vol. 52; ISSN CORRAK; ISSN 0010-9312
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
BENDING
CHLORIDES
CONTAINERS
CORROSION RESISTANT ALLOYS
CORROSIVE EFFECTS
CRACK PROPAGATION
INCOLOY 825
MATERIALS TESTING
MECHANICAL TESTS
PASSIVATION
PITTING CORROSION
RADIOACTIVE WASTE DISPOSAL
STAINLESS STEEL-316L
STRESS CORROSION
TEMPERATURE DEPENDENCE
THIOSULFATES