SYMPOSIA PAPER Published: 01 January 1979
STP38115S

Slow Strain-Rate Stress Corrosion Testing for Liquid Metal Fast Breeder Reactor Steam Generator Applications

Source

A high-temperature slow strain-rate facility was developed to evaluate the stress corrosion resistance of alloys considered for the construction of liquid metal fast breeder reactor (LMFBR) steam generators. The primary concern was stress corrosion that might occur on the water side during steam generator operation in locally faulted caustic environments. Most of the studies were performed at 316°C in 5 or 10 percent sodium hydroxide (NaOH) solutions with 2¼Cr-1Mo steel and Incoloy-800.

With minor modification, the slow strain-rate test was converted to a straining electrode test. Experiments conducted by the straining electrode test permitted the study of stress corrosion behavior in the high temperature caustic solutions over a range of oxidizing potentials.

It was found that 2¼Cr-1Mo steel was extremely resistant to caustic cracking at 316°C in all metallurgical conditions tested by the slow strain-rate test and the straining electrode test. A few slow strain-rate tests performed at 232 °C in 5 to 10 percent NaOH resulted in intergranular and transgranular stress corrosion failures of 2¼Cr-1Mo steel.

Unlike 2¼Cr-1Mo, Incoloy-800 was susceptible to caustic cracking at 316°C. The susceptibility depended on the metallurgical condition and to some extent, the oxidizing potential. The cold-worked and Grade 1 conditions exhibited excellent resistance to caustic cracking in the slow strain-rate test. However, limited studies in the straining electrode test showed the Grade 1 condition could be readily cracked at anodic oxidizing potentials.

Author Information

Indig, ME
General Electric Company, San Jose, Calif.
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Details
Developed by Committee: G01
Pages: 170–202
DOI: 10.1520/STP38115S
ISBN-EB: 978-0-8031-5548-0
ISBN-13: 978-0-8031-0579-9