Selective corrosion study by anodic stripping of CrNi steel

A method consisting in galvanostatic anodic stripping of layers with thicknesses of the order of nanometers combined with gamma-spectrometric analysis of soluble anodic reaction products has been developed for the purpose of a study of concentration profile of alloy components in the surface of alloys after a corrosion process.Suitable conditions as regards the stripping solution and the electrochemical parameters were investigated to ensure reliable determination of the quantity of stripped metal based on the Faraday relationship and to provide for a uniform removal of metal from the surface. Experimentally verified constants for the conversion of passed electric charge to stripped layer thickness are given for steel grades FeCr17, FeCr18Ni5Mn9, FeCr18Ni9, FrCr18Ni10Mo2 and FeCr20Ni38Mo6, the average accuracy being ±1.5 per cent.Two examples are presented to illustrate the determination of the concentration profile of components in the surface of steel grade FeCr18Ni9.