Electrochemical corrosion, hydrogen permeation and stress corrosion cracking behavior of E690 steel in thiosulfate-containing artificial seawater

Abstract

Electrochemical corrosion and stress corrosion cracking (SCC) behavior of E690 steel in the aerated, deaerated, acidified and thiosulfate-containing artificial seawater are investigated. Corrosion product is transformed from a single iron oxyhydroxide layer to a stratified structure with an additional outer mackinawite layer after long-time immersion with addition of thiosulfate. The SCC process at low thiosulfate concentration (10−4 M) is mainly dominated by hydrogen embrittlement because of the thiosulfate-induced promotion of hydrogen permeation. At high thiosulfate concentration (10−2 M), occurrence of severe pitting corrosion leads to the highest SCC susceptibility despite that the formation of continuous mackinawite inhibits hydrogen permeation.