Hydrogen permeation and stress corrosion cracking of heat-affected zone of E690 steel under the combined effect of sulfur species and cathodic protection in artificial seawater

Abstract

Electrochemical corrosion, hydrogen permeation, and stress corrosion cracking (SCC) behavior of E690 steel and the simulated heat-affected zone (HAZ) microstructures, i.e., intercritical heat affected zone (ICHAZ), fine-grained heat-affected zone (FGHAZ), coarse-grained heat-affected zone (CGHAZ), in the aerated, deaerated, acidified and thiosulfate-containing artificial seawater (ASW) at open circuit potential and −850 mVSCE are investigated. The results show that both sulfur species and cathodic protection promote hydrogen permeation and SCC susceptibility, and the combination of the two effects intensifies hydrogen permeation and SCC. Sulfur species and cathodic protection gradually increase the leading role of hydrogen embrittlement in cracking mechanisms. CGHAZ has the worst corrosion resistance, in ASWs. In the deaerated, acidified ASW with thiosulfate at −850 mVSCE, the SCC susceptibility of ICHAZ is the highest because of the structural heterogeneity and high pinning H content, attributed to the interfaces and their ability to accommodate H atoms.