Stainless steel is increasingly widely used, mainly because the material is corrosion-resistant and not easy to rust; usually, stainless steel manufactured parts have a long life.
However, stainless steel is the most easily misunderstood material because of its name – stainless steel.
Usually, processing stainless steel products needs extra measures to prevent rust. That is to say, stainless steel finished products should finally go through surface rust treatment to avoid various corrosion accidents in future use.
If there are no plating or coating requirements, stainless steel parts generally have to be pre-treated (including pickling, polishing, etc.) and then passivation treatment to be used as a finished product or assembled into components. Facts show that only after the last passivation treatment, stainless steel can maintain long-lasting stability and improve corrosion resistance.
Generally, there are strict specifications for the passivation process of operation control and quality inspection of the passivation film.
The benefits of stainless steel passivation
(1) Improve the thermodynamic stability of stainless steel in environmental media. After the passivation of stainless steel, the metal potential order is in a more positive position, similar to the precious metals, chemical stability, and not passivated stainless steel for the activation state, in a more negative potential position, similar to ordinary steel.
(2) Prevention of localized corrosion of stainless steel. General stainless steel is prone to a variety of corrosion, including pitting corrosion, intergranular corrosion, wear corrosion, corrosion fatigue, etc., which are related to the surface state. Passivation can eliminate the possibility of any corrosion.
(3) Passivation makes the stainless steel surface sufficiently clean. Passivation can remove metal contaminants from the surface layer of stainless steel, as well as impurities embedded in stainless steel, such as copper, zinc, cadmium, and lead, as well as low-melting metals, free iron, so that the chromium and nickel contained in the surface is enriched and stabilized. The contamination of these metals can easily lead to corrosion damage of stainless steel.
(4) Eliminate the hot working oxides on the stainless steel surface. In the passivation process using a nitric acid solution containing hydrofluoric acid Liquid, both leaching oxides and passivation of the surface.
(5) Passivation treatment as a post-treatment, stainless steel is required to have a variety of pretreatment. Including sandblasting, shot blasting, and electrochemical Improvement of stainless steel surface conditions such as chemical polishing and polishing before passivation.