Effect of Carbide Structure on the Corrosion Resistance of Steel^★

Although carbon steel is not generally regarded as a very corrosion-resistant material, there are a number of services in which it is attacked only slowly because of the protective nature of solid corrosion products formed on the surface. This fact is of great economic significance. It makes possible the large-scale use of steel in handling such corrosive chemicals as concentrated sulfuric and hydrofluoric acids. It is probably of far greater importance in the life of steel oil-well equipment than has been generally recognized. The corrosion products formed by the attack of oil-well fluids on steel are mostly insoluble. As a result, much of the surface is protected from further rapid attack, once a film of corrosion products has formed. On some parts and in some areas, however, this film either does not adhere, or is of too permeable a nature to stop diffusion of corrosive agents to the metal surface;...