すき間を有する SUS304 ステンレス鋼の腐食挙動に及ぼす超音波印加の影響

Abstract

Anodic polarization testing of SUS304 stainless steel with crevice was carried out in an aqueous solution of 3.5 mass%NaCl at a potential increasing at a constant rate of 0.33 mV/s. When the current density reached 10, 12 or 50 A/m2, the potential was kept at a constant value for a constant period. When an ultrasonic wave (UW) was applied to the specimen during the holding period of the potential, the current density on the specimen surface was compared to that without the application of UW. Crevice corrosion and pitting corrosion were found on the specimen after the polarization test. The corrosion of specimen was largely decreased when UW was applied to the specimen. The current density almost synchronized with the cyclic application and stop of UW. The suppression of crevice corrosion and pitting corrosion in the specimen is attributed to the decrease in the enrichment of hydrogen ions and chloride ions in the crevice or pits by the stirring effect of UW.