Study on the pitting corrosion behavior of X65 steel in supercritical and dense-phase CO2 based on in-situ electrochemical noise measurement

Abstract

There is a lack of electrochemical measurements and analysis in supercritical and dense-phase CO₂ environments due to the difficulty in conducting in-situ electrochemical tests. This study constructed a novel in-situ electrochemical noise (EN) testing system for supercritical and dense-phase CO₂ corrosion, and the influences of water content and phase state on the corrosion kinetics of pipeline steel were investigated. The results show that metastable pitting and stable pitting coexisted to dominate localized corrosion in supercritical conditions, while stable pitting predominated in dense-phase environments. The differences in pitting corrosion mechanism were further analyzed by the SEM and 3D profilometer characterizations.