Understanding Localized CO2 Corrosion of Carbon Steel from Physical Properties of Iron Carbonate Scales

Abstract

Abstract New data on the fracture mechanical properties (Young’s modulus, fracture stress, fracture strain, internal stress, intrinsic stress, and adhesion) and electrical resistance of iron carbonate scales from CO2 corrosion of carbon steel are reported and discussed with respect to mechanistic considerations on localized attack in CO2 corrosion. The cracking and spalling of iron carbonate scales is primarily due to intrinsic stresses. Inhibitors influence the fracture mechanical properties by reducing the thickness of the scales and their intrinsic growth stresses. FILC is initiated at sites of local spalling if critical flow intensities prevent reformation of protective scales. The electronic conductivity of iron carbonate scales is too low to be considered as site of the cathodic reaction of the electrochemical corrosion process.