Hydrostatic pressure effects on corrosion behavior of X70 pipeline steel in a simulated deep-sea environment

Hydrostatic pressure (HP) effects on corrosion process of X70 steel in 3.5% NaCl solution have been investigated by situ electrochemical impedance spectroscopy (EIS), immersion tests and Raman spectra. These results indicate HP affects the corrosion behavior of the X70 steel during the whole immersion period. At the initial immersion, HP promotes the electrochemical reaction of corrosion process. Pitting initiation rate and propagation are both promoted by HP, corrosion rate increases with HP at the initial immersion period. At the stable immersion period, inner layer corrosion product is complete at 0.1 MPa, obvious cracks can be observed at 10 MPa. HP promotes Cl− transport and adsorption on the rust layer, corrosion rate slightly increases with HP.