Intergranular oxidation behavior of austenitic stainless steel in high temperature and high pressure water

Soma, Yasutaka   ; Kato, Chiaki   ; Ueno, Fumiyoshi  

Within crevice of austenitic stainless steel (solution treated, mirror poloshed) immersed in high-temperature water (561K, 8.5MPa, dissolved oxygen conc. 32ppm, conductivity ca.1 to 1.5e-6S/cm), new form of intergranular oxidation was occured. The intergranular oxidation occured in certain area within the crevice, that is, the area with relatively low crevice gap and distant from the crevice mouth. Cr was enriched in the oxide and the oxidation occured both grain boundary and grain matrix. After the intergranular oxidation, some grain was loosen and peered off. Maximum depth of the intergranular oxidation was 50e-6m/500h. Because almost no stress was applied on the specimen, relationship between this oxidation bahavior and stress corrosion cracking should be clarified by further experiment.