Mechanisms to understand high electrical conductivity of solution within crevice of stainless steel in high temperature water

Soma, Yasutaka   ; Komatsu, Atsushi ; Ueno, Fumiyoshi  ; Inagaki, Hiromitsu*

Corrosion condition within crevice of stainless steel is important to understand dissolution mechanisms of crack tip of stress corrosion cracking (SCC) in high-temperature water. We have reported that electrical conductivity of solution within crevice of stainless steel (crev) exposed to high temperature and high purity water containing sufficient dissolved oxygen (DO) become more than 2 orders of magnitude higher than that for bulk pure water. In this study effect of conductivity and DO concentration of bulk water on crev of Type-316L stainless steel have been studied in 288C water. Following conclusion have been obtained: (1) crev increased with increasing DO concentration from 3 ppb to approximately 300 ppb. Above 300 ppb, crev did not simply increased with DO concentraion. (2) maximum crev was not affected by bulk water conductivity suggested that crev would be determined by chemical equilibrium reaction. (3) crev-time curves were not affected by crevice depth. It was assumed that anion required to increase crev generated within the crevice.