Abstract
Corrosion potential fluctuation of SUS 304 stainless steel during induction period of localized corrosion was measured in 4.0mol/l NaCl solution. The solution was exposed to air and its temperature was kept at 353K.
It was found that new type of the potential fluctuation (Type II), differ from the potential fluctuaiton generally reported (Type I). From the result of SEM observation, the number of Type II and the number of micropits were agreed. In order to investigate the correlation between potential fluctuation and micropit, it was thought up that new method to estimate the local anode current quantitatively from the observed potential fluctuation.
The observed corrosion potential fluctuation was applied to the specimen by a potentiostat and the change of the cell current (response current) was measured. Pit radius estimated from the integral of the response current was in good agreement with the radius of micropit evaluated from SEM micrograph.
