2018 Volume 67 Issue 5 Pages 222-228
Localized corrosion in crevice of SUS316 stainless steel after immersion in 288℃ high purity water with dissolved oxygen concentration of 32 ppm for 100 h was analyzed. Two different types of localized corrosion initiated on grain boundary and inclusions. The former initiated on grain boundary and oxide grown into grain matrix. The oxidized area showed duplex structure composed of microcrystalline FeCr2O4 and island-shaped residual metals. The latter initiated on inclusions containing Ca and S and microcrystalline FeCr2O4 grown into metal matrix. These localized corrosion occurred selectively in oxygen depleted area indicated formation of macroscopic corrosion cell with the corroded area as anode and surrounding oxygenated area as cathode.
