ANODIC POLARIZATION BEHAVIOR IN CREVICE CORROSION OF STAINLESS STEELS IN HOT WATER AND EVALUATION OF CORROSION RESISTANCE BY MEASUREMENTS OF COUPLE CURRENT AND CORROSION POTENTIAL.

To evaluate corrosion resistance of stainless steels in hot water containing about 25-30 ppm Cl** minus at max. 80 degree C, anodic polarization measurements and corrosion tests were carried out on the specimens having various types of crevice. Initiation of crevice corrosion was accelerated by the existence of active sites such as oxide films with the residue of vaporized tap water on the specimen surface. Based on the change in couple current between crevice-containing and crevice-free specimens, pitting inside the crevice appeared to grow early in the test period and to become inactive thereafter. On the other hand intergranular corrosion and SCC (stress corrosion cracking) appeared to continue through the test periods.