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Alloy steel; Atmospheric corrosion; Catalysis; Cracks; Electrolytes; High strength steel; Hydrogen; Offshore oil well production; Oxygen; Residual stresses; Seawater corrosion; Steel corrosion; Strain rate, Corrosion morphology; Critical oxygen concentrations; Marine atmosphere; Offshore facilities; Oxidation of hydrogen; Oxygen concentrations; Slow strain rate tensile test; Thin electrolyte layer, Stress corrosion cracking
Abstract:
The mechanism of stress corrosion cracking (SCC) of E690 high-strength steel in a marine thin electrolyte layer (TEL) was investigated by performing in-situ mechanical–electrochemical tests, slow strain rate tensile (SSRT) tests, and characterization of corrosion morphology. It was concluded that E690 steel was highly sensitive to SCC, which was jointly determined by local anodic dissolution (AD) and hydrogen embrittlement (HE) both caused by dissolved O 2 . In addition to these functions, hydrogen oxidation catalyzed by ferric ion was found. There was a critical oxygen concentration, approximately 21 by volume, between these two different roles. Below this value, the increase in the oxygen concentration promoted the synergistic effect of AD and HE, resulting in the increase in SCC susceptibility. However, above this value, worse general corrosion offset crack initiation as well as the oxidation of hydrogen catalyzed by ferric ions reduced the SCC susceptibility. © 2018 Elsevier Ltd
