Electrochemical Evaluation for Sensitization of Austenitic Stainless Steels Using Neutral Solution

摘要

Austenitic stainless steels (JIS SUS 304) weresensitized at 923K for various times and the extent of sensitizaitonwas evaluated in 0.6kmol/m~3 NaCl solution, using twoelectrochemical methods: cyclic voltammetry and potential stepchronoamperometry. Cyclic voltammograms indicated thatsensitized specimens had two types of pitting corrosion, one forchromium depleted zone and the other for grains. This pittingpotentials for both types of corrosion measured by cyclicvoltammetry had no significant relation to the extent ofsensitization. Potential step chronoamperometry was then appliedto the evaluation. The potential step chronoamperometry to thepitting potential for grains gave no significant correlation with thesensitization, and the plotted data were scattered randomly. On theother hand, the time integral of current density calculated frompotential step chronoamperometry at the pitting potential forchromium depleted zone increased with the extent of sensitization.The latter case can be utilized for the evaluation of sensitization.