Crevice Corrosion of Mild Steel Assemblages in Quiescent Seawater Under Extended Exposure Periods

Crevice corrosion is a known issue for high chromium steels exposed to seawaters. However, it occurs also for mild and low alloy steels. Herein observations are reported for initiation and corrosion progression of mild steel. Crevices 30 to 200 µm in size, with outstands up to 100 mm, were considered, all exposed for up to 4 years in quiescent Pacific Ocean seawater. Both corrosion losses and pit depths on surfaces exterior to crevices increased with nitrate dosing but decreased for filtered UV‐treated seawater. Corrosion loss and pit depths were more severe on surfaces exterior to crevices. Both showed bi‐modal trending with continued exposure.