PROCEDURE FOR DECAPING AND PASSIVING OF SPECIAL STEEL.

摘要

Procedure for pickling and / or passivating of special steel, in which the special steel is contacted with an aqueous solution for the treatment with a pH value less than or equal to 2.5, with a temperature in the range of 30 to 70 ° C, containing from 15 to 100 g / l of iron ions, characterized in that Fe (II) is oxidized, formed during the pickling process, to the trivalent level, using a treatment solution, which contains at least 10 g / l of Fe (III) ions as well as hydrofluoric acid as essential components in a concentration from 1 to 60 g / l and which is free of nitric acid, contacting the solution for treatment, for steel pickling special austenitic, in the presence of 50 to 600 mg / l of cupric ions (II), for the pickling of special martensitic, ferritic or hardened by segregation or double steel, in the presence of 50 to 300 mg / l of copper ions, with oxygen