Stress-corrosion crack initiation process for Alloy 182 weld metal in simulated BWR environments
- Ishikawajima-Harima Heavy Industries Co., Ltd., Tokyo (Japan). Research Inst.
For preventing SCC from occurring in the internal structure of materials of the BWR plant, the injection of hydrogen into the core-water so as to reduce the free corrosion potential of the materials were proposed. Because of the lack of basic data of stress-corrosion cracking susceptibility in BWR environment on Ni-based alloys in comparison with stainless steels, the slow strain-rate tensile (SSRT) tests and the creviced bent-beam (CBB) test were conducted for a sensitized Alloy 182 weld metal in high-purity water environments containing dissolved oxygen (DO) and hydrogen (DH) to varied concentrations at 288 C, and the SCC initiation process were examined. The susceptibility of a material to SCC was discussed in terms of the electrode potential effect, and the effects of impurities of the testing water were examined by adding slightly Na{sub 2}, SO{sub 4}. In high purity waters and in the electrode potential region higher than {minus} 0.2 V vs. SHE, the interdendritic stress-corrosion cracks were observed both in the slow strain-rate test and the creviced bent-beam test. SEM observations of sub-cracks at the specimen surfaces revealed that stress-corrosion cracks were initiated when the oxide film had cracked to under-hundred {micro}m wide, that no such individual cracks could grow per se, but that those micro-cracks which happened to be formed in each other`s vicinity would coalesce into large cracks, one of which made propagated as stress-corrosion cracking, and that the stress-corrosion cracking sensitivity became more acute on addition of impurity. In the electrode potential region lower than 0 V, on the other hand, the stress-corrosion cracks were observed to be initiated at bottoms of corrosion pits formed on the specimen surfaces in the former, whereas both type of stress-corrosion cracks were observed between 0 to {minus}0.2V. No stress-corrosion crack was observed even though much the same corrosion pits in the CBB test at {minus}0.4 V.
- OSTI ID:
- 99550
- Report Number(s):
- CONF-950304--
- Country of Publication:
- United States
- Language:
- English
Similar Records
Effects of Cr and Nb contents on the susceptibility of Alloy 600 type Ni-base alloys to stress-corrosion cracking in a simulated BWR environment
General and localized corrosion of carbon and low-alloy steels in oxygenated high-temperature water. Final report. [BWR]
Related Subjects
36 MATERIALS SCIENCE
BWR TYPE REACTORS
CHEMICAL COMPOSITION
CHROMIUM ALLOYS
CRACK PROPAGATION
EXPERIMENTAL DATA
FILLER METALS
INCONEL 600
IRON ALLOYS
MANGANESE ALLOYS
MECHANICAL TESTS
NICKEL BASE ALLOYS
NIOBIUM ALLOYS
REACTOR COMPONENTS
REACTOR MATERIALS
SCANNING ELECTRON MICROSCOPY
SODIUM SULFATES
STRESS CORROSION
WATER CHEMISTRY