Influence of pH of Silt on the Early Electrochemical Corrosion Behavior of X70 Steel

The early electrochemical corrosion behavior of X70 steel in silt environment with different pH values was studied by means of electrochemical impedance spectroscopy (EIS), polarization curves and scanning electron microscopy (SEM). The results show that the corrosion of X70 steel in acidic (H₂SO₄), alkaline (NaOH) and neutral silt was different obviously. In simulated acid silt, the free corrosion potential of X70 steel in the silt of pH 5 was obvious higher than that in the others after 21 d. The corrosion rate of X70 steel decreased with the increase of pH (4~5). In the simulated alkaline silt, the corrosion behavior of X70 steel was greatly affected by the OH^- ions in liquid medium, and the corrosion rate of X70 steel increased with the pH (9~11) increasing.