Localized corrosion in crevice of SUS316 stainless steel in oxygenated high temperature and high purity water

Soma, Yasutaka; Ueno, Fumiyoshi

Zairyo To Kankyo, 67(5), p.222 - 228, 2018/05

Localized corrosion in crevice of SUS316 stainless steel after immersion in 288C 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 FeCrO and island-shaped residual metals. The latter initiated on inclusions containing Ca and S and microcrystalline FeCrO 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.