Electrochemical impedance spectroscopy analysis of X70 pipeline steel stress corrosion cracking in high pH carbonate solution

In this study, electrochemical impedance spectroscopy (EIS) technique was used to investigate the development of stress corrosion cracking (SCC) in X70 pipeline steels. Slow strain rate testing (SSRT) was performed on steel samples in high pH bicarbonate solution. Potentiostatic EIS tests were also conducted regularly to determine the changes associated with the SCC. The Bode modulus and phase diagrams for cracks were calculated. Furthermore, the suitable frequency window for detection of the cracks by EIS was determined. Finally, a circuit model proposed for the cracking.

► Calculation of impedance data for cracks during slow strain rate testing.
► Proposing a circuit model for stress corrosion cracking of X70 pipeline steel.
► Finding a frequency window for detection of cracks by EIS.
► Trend of phase angle shift and impedance modulus for X70 steel during SSRT.