The electrochemical corrosion and stress corrosion cracking (SCC) behaviors of X70 pipeline steel in CO2-containing solution were studied by electrochemical measurements, slow strain rate tensile tests, and surface characterization. The results found that the electrochemical corrosion of X70 steel in aerated, alkaline solution is an activation-controlled process, and a stable passivity cannot develop on steel. Corrosion rate of the steel increases with the CO2 partial pressure. The enhanced anodic dissolution due to the additional cathodic reaction in the presence of CO2, rather than the film-formation reaction, dominates the corrosion process. The mass-transfer step through FeCO3 deposit is the rate-controlling step in corrosion of the steel. The susceptibility of steel to SCC and the fracture brittleness increase with the CO2 partial pressure. The enhanced fracture brittleness is attributed to the evolution and penetration of hydrogen atoms into the steel, contributing to crack propagation. The formed deposit layer is not effective in reducing hydrogen permeation due to the loose, porous structure.
Corrosion and stress corrosion cracking behavior of X70 pipeline steel in a CO2-containing solution
Journal of Materials Engineering and Performance ; 18 , 3 ; 319-323
2009
5 Seiten, 14 Quellen
Article (Journal)
English
alkalische Lösung , amorphes Metall , Bruchmechanik , Dehnungsgeschwindigkeit , Eigenspannung , Eisencarbonat , elektrochemische Korrosion , kathodische Reaktion , Kohlendioxid , Korrosionsgeschwindigkeit , Korrosionsprüfung , Pipeline-Schaden , Plastizität , Porenstruktur , Rohrstahl , Spannungsrisskorrosion , Sprödigkeit , Wasserstoffversprödung , Zugfestigkeitsprüfung , anodische Auflösung , Wasserstoffdurchlässigkeit
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