Propagation analysis of crevice corrosion on SUS304 stainless steel under potentiostatic condition in artificial sea water

摘要

© 2015 Japan Society of Corrosion Engineering. All rights reserved.The propagation behavior of crevice corrosion on SUS304 was investigated by the new crevice corrosion test apparatus. The corrosion area and corrosion current in glass/metal crevice can be measured at the same time by this apparatus. The specimen was polished just before the crevice corrosion test under the constant potential condition, E=299 mV, 399 mV and 499 mV (SHE), in artificial seawater at room temperature. Some important results were obtained. The crevice corrosion initiation time tVI determined by the visual observation was coincident with tINCU determined by the current density change. The crevice corrosion area, ACREV, increased exponentially with time from the crevice corrosion initiation time. However, the increasing rate of the crevice corrosion volume, VCREV, changed at the time, tR, which crevice corrosion reached at the edge of crevice. We divided the corrosion process into two stages, Region I and Region II. Region I and Region II are defined as the time region before and after tR respectively. The increasing rate of VCREV in Region II was larger than that in Region I. However, the increasing rate of ACREV in Region I was slightly larger than that in Region II.