wet and wet process acid solution free of chromium for treating protection against corrosion of steel surfaces

Process for the protective treatment against corrosion of metal surfaces without covering, representing at least partially steel surfaces, which are brought into contact the metal surfaces with an acidic aqueous solution of a fluorocomplejo at least one element M selected group B, Si, Ti, Zr and Hf, washed with water and then coated with an electrophoretic varnish dip that can be deposited cathodically, characterized in that a) the aqueous solution contains no more than 1 mg / l of organic polymer with allylamine or vinylamine monomers, B) the aqueous solution contains a buffer system for the pH range of 2.5 to 5.5, C) the aqueous solution additionally contains at least one component selected from: nitrate ions, copper, silver ions, vanadium or vanadate, bismuth ions, magnesium ions, zinc ions, manganese ions, cobalt ions, nickel ions, tin ions, carboxylic acids aro matic with at least two groups containing donor atoms or derivatives of such carboxylic acids, silica particles with an average particle size below 1 micron, D) the metal surface is dried after contacting with the aqueous solution of fluorocomplejo and before coating with the electrophoretic dip lacquer can be deposited cathodically that