Thursday, March 20, 2008 - 9:30 AM
Convention Center, Second Level, 210 (Ernest N. Morial Convention Center)
08596

Effect of Grain Boundary Carbide on IGSCC Growth of Austenitic Stainless Steels in High-Temperature Pure Water

Takuyo Yamada, Takumi Terachi, and Koji Arioka, Inst of Nuclear Safety Sys Inc

In order to evaluate the influence of grain boundary carbide precipitation on IGSCC growth rate of cold-worked stainless steels, crack growth rate tests were performed under aerated and deaerated pure water environments at 320°C using half-inch size compact tension (CT) specimens. In this study, the influence of (1)amount of grain boundary carbide, (2)Mo in alloys and (3) Cr depletion at the grain boundary on the IGSCC growth behavior in stainless steel was studied under those water environments at 320°C.

   As a result, (1) IGSCC growth was observed on non-sensitized CW20%316 and CW20%304 under aerated and 0.3-ppm hydrogenated pure-water environment at 320°C. (2) IGSCC growth was not observed for sensitized CW20%316 (at 650°C x 48h) and CW20%304 (at 650°C x 24 h) and healing heat-treated CW20%316 (at 650°C x 48 h + 900°C x 0.5 h) under the 0.3-ppm hydrogenated water environment. (3) The results showed that the susceptibility of CW316 and CW304 to IGSCC was inhibited by the precipitation of grain boundary carbide under deaerated environment. The result suggested quite different behavior from that in an oxygenated high-temperature water environment.


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