Application of electrochemical noise to monitor stress corrosion cracking of stainless steel in tetrathionate solution under constant load

Electrochemical noise measurements were applied to study the initiation and propagation of intergranular stress corrosion cracking in sensitised stainless steel under constant load. Characteristic current transients were identified and assigned to different corrosion processes. One type of transient was very similar to signals related to initiation and propagation of single micro cracks, which were found in an earlier study using the electrochemical microcapillary technique. Other signal types were assigned to metastable pitting events, crack coalescence events or crack growth. Crack propagation could be explained by localised metal dissolution along Cr-depleted grain boundaries.

► Electrochemical noise of SCC on stainless steel was monitored at constant load.
► Characteristic current transient indicated different corrosion processes.
► Crack growth is explained by anodic dissolution of sensitised grain boundaries.
► Large current transients are explained by coalescence of micro cracks.
► Current signals are compared to an earlier study on the micro scale.