Investigation of Q235 steel electrochemical corrosion behavior in naturally dried sandy soil

Abstract

Based on electrochemical technology, the electrochemical corrosion behaviour of Q235 steel in sandy soil under naturally dried condition was studied comprehensively from two aspects: Q235 steel and sandy soil. The results show that the sandy soil is basically neutral and the temperature fluctuates around 20 ℃ under naturally dried condition. The moisture in the sandy soil gradually dries from the initial saturation state of 30 % within 14 d. The impedance spectrum shows that at 5 d, corrosion of Q235 steel is greatest when the radius of capacitive arc reaches a minimum. The variation law of modulus and phase angle with water is consistent with the impedance spectrum. After 5 d, modulus and phase angle fluctuates greatly in the frequency domain of 103∼105 Hz. The polarization curve shows that when the moisture content is 10.2 %(7 d), the polarization curve of Q235 in the sandy soil corresponds to the highest corrosion current density, which is moderate corrosion, and the rest is mild corrosion. The average corrosion rate is 1.51E-2 mm/a. Various thicknesses of brown-yellow corrosion products (Fe2O3) have accumulated on the surface of Q235 steel, showing honeycomb, flocculent, etc. formations. The corrosion of Q235 steel in local areas is strong, and more corrosion pits are formed.