CO2 corrosion experiments of X70 steel with and without silica sand were performed by using high temperature and high pressure (HTHP) autoclaves at fluid velocities of 1m/s and 2m/s, respectively. The corrosion rates were measured, the macro and micro morphology of the corrosion scale and the steel matrix were analyzed and the thicknesses of the corrosion scale were measured. Electrochemical Potentiodynamic Polarization Curves (EPPCs) and Electrochemical Impedance Spectroscopy (EIS) of X70 steel with and without corrosion scale at different velocities were measured and analyzed. The results showed that the erosion corrosion morphology with sand was uniform corrosion while the corrosion morphology without sand was localized corrosion. Corrosion scale under sand containing condition consisted of two layers, which was the same as the condition without sand. The resistances of the inner layers of the scale were much bigger than those of the outer layers, and the protective effect of the inner scale was predominant. The resistance of the scale at the velocity of 2m/s was larger than that of 1m/s when the sands existed in the fluids, while the result was opposite when no sand existed.

Subject
Scale morphologies, Electrochemical impedance spectroscopy, Sand, Flow velocity, Corrosion scales, Fluids, Metals, Scale formation, Steel, Corrosion protection, Corrosion resistance, Erosion corrosion, Grain
Keywords:
erosion corrosion, silica sand, CO2 corrosion, corrosion scale, X70 Steel
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2012
Association for Materials Protection and Performance (AMPP)
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