The influence of copper, molybdenum and silicon on the corrosion electrochemical behavior of austenite chromium-nickel steel

The role of copper, molybdenum and silicon in the anodic behavior of a X16H14 type steel in a sulfuric acid solution is investigated with the use of tracer technique. It is shown that molybdenum and copper enhance its corrosion resistance by slowing down active dissolution and faclitating the steel passivation. With regard to these characteristics, copper, especially if combined with silicon, is superior to molybdenum. Silicon does not affect these properties in the absence of copper and molybdenum but enhances the susceptibility of a copper-containing steel to intergranular corrosion. The iron-chromium-nickel base of steels, in turn interacting with the solution, activates the dissolution of the alloying copper and molybdenum. The results are interpreted in terms of active centers causing the surface reactivity.