Electrochemical Characterization of X60 Steel Exposed to Different Soils from South of México

Abstract

Physicochemical effect on the corrosion process of API X60 steel exposed to five types of soils from south of Mexico at different moisture content was carried out. Two soils were collected in the state of Veracruz (clay of high plasticity and silt) and three soils from the state of Campeche (clay, sand, and clay-silt). Moisture values were determined by addition of 0, 20, 40, and 60 mL of deionized water in a volume of 125 cm3 of each soil. Physicochemical effect of the different soils on the corrosion process of X60 steel was evaluated through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves (PCs). Effect of the damage on the coating when the steel is exposed to corrosive soils was studied. The three more corrosive soils (clay, sand, and clay-silt) were used to evaluate the corrosion behavior with a viscoelastic coating with a simulated damage. The higher corrosion rate obtained from polarization curves for uncoated X60 steel was found in the clay (0.379 mm/year) with 39.7 wt.% of moisture content. Steel coated with a simulated damage indicates that the clay-silt (52.3 wt.%) was the most aggressive soil for X60 steel (0.0029 mm/year).