Factors affecting the potential of galvanostatically polarised pipeline steel in relation to scc in co2?3-hco-3 solutions

The relationship between potential and applied cathodic current density for steel in CO^2-₃-HCO^-₃ solutions is affected by the nature of the oxides on the steel, temperature and solution composition. The presence of Fe₃O₄, a major constituent of mill scale, on the surface can promote potentials within the range where stress corrosion cracking is possible, under galvanostatic conditions simulating the application of cathodic protection to a pipeline. The combinations of potential and pH under which form the various solid reaction products, identified by X-ray diffraction and optical microscopy, can be related thermodynamically to the relevent electrochemical reactions.