Grain boundary segregation and intergranular stress corrosion cracking susceptibility of austenitic stainless steels in high temperature water
- Tohoku Univ., Sendai (Japan)
- Massachusetts Institute of Technology, Cambridge, MA (United States)
The effects of grain boundary segregation on intergranular stress corrosion cracking of austenitic stainless steels in high temperature water have been examined as a function of heat treatment. The materials investigated were: (1) two commercial purity Type 304; (2) low sulfur Type 304; (3) nuclear grade Type 304; (4) ultra high purity Type 304L; and (5) Type 316L and Type 347L. Specimens were solution treated at 1050{degrees}C for 0.5 hour and given a sensitization heat treatment at 650{degrees}C for 50 hours. Some of the specimens were then subjected to an aging heat treatment at 850{degrees}C for from one to ten hours to cause Cr recovery at the grain boundaries. The effects of heat treatments on degree of sensitization and grain boundary segregation were evaluated by Electrochemical Potentiokinetic Reactivation (EPR) and Coriou tests, respectively. The susceptibility to stress corrosion (SCC) was evaluated using slow strain rate tests technique (SSRT) in high temperature water. SSRT tests were performed in an aerated pure water (8 ppm dissolved oxygen) at 288{degrees}C at a strain rate of 1.33 x 10{sup {minus}6}/sec. Susceptibility to intergranular stress corrosion cracking was compared with degree of sensitization and grain boundary segregation. The results of the investigation indicate that EPR is not always an accurate indicator of SCC susceptibility. The Coriou test provides a more reliable measure of SCC susceptibility especially for 304L, 304NG, 316L, and 347L stainless steels. The results also indicate that grain boundary segregation as well as degree of sensitization must be considered in the determination of SCC susceptibility.
- OSTI ID:
- 48117
- Report Number(s):
- CONF-910808--
- Country of Publication:
- United States
- Language:
- English
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