Abstract
Transient behaviors of corrosion current of Type 316 stainless steels during a slow strain rate test (SSRT) in high-purity oxygenated water at 288°C were investigated and their correlation with stress corrosion cracking (SCC) was discussed. Corrosion current at corrosion potential between a specimen under slow-rate straining and a counter electrode which was made of the identical alloy to the specimen was continuously monitored using a zero resistance ammeter. Spike-like current pulses were observed after yielding. The current pulses had short rise-time, typically a few seconds, and slow decay behavior, 100-1000 seconds; This characteristic was considered to correspond to the slip dissolution processes. Although the current pulses were observed both on the solution treated material and on the sensitized one, characteristics of the current pulses reflected well the difference in SCC susceptibility of the samples. Current pulses from the sensitized material had higher peak and slower decay rate than those from the solution treated one. Capability of the current noise monitoring for detecting SCC initiation in austenitic stainless steels in high-temperature high-pressure water was demonstrated and it was suggested that the current noise can provide real-time evaluation of SCC behavior.
