YUHONG GROUP - Surface treatment of Stainless Steel Flange

I. Surface treatment of stainless steel Surface Treatment of Stainless Steel: Natural white treatment Mirror bright treatment method Colour treatment

1. Surface blackening: Stainless steel flanges are blackened and oxidised in the course of processing, either by rolling, trimming, welding, or by fire and heat treatment of the surface of the workmanship. This hard black oxide was previously removed by strong corrosion using hydrofluoric acid and nitric acid. However, this method is costly, polluting to the environment, harmful to the human body, and highly corrosive, and has been gradually phased out. The current treatment methods for oxides are mainly sandblasting and chemical methods.

(1) Sand blasting (shot blasting) method: The blackish oxidised surface is mainly removed by spraying micro-glass beads.

(2) Chemical method: A non-contaminating pickling passivation paste and a room-temperature, non-toxic cleaning solution with inorganic additives are used for immersion washing. The purpose of whitewashing is to achieve the intrinsic colour of the stainless steel flange. This method is more appropriate for large, complex products.

2. Surface surface brightening treatment method: According to the complexity of stainless steel flange products and the different requirements of users, mechanical polishing, chemical polishing, electrochemical polishing and other methods can be used to achieve a mirror luster.

3. Surface colouring treatment: The colouring of stainless steel flanges not only gives stainless steel flange products a variety of colours and increases the variety of colours in the products, but also improves the abrasion and corrosion resistance of the products.

There are five ways to colour stainless steel flanges:

(1) The chemical oxidation coloration method; that is, the formation of a film colour by chemical oxidation in a specific solution.
(2) The electrochemical oxidation method; the colour of the film formed by electrochemical oxidation in a specific solution.
(3) Ion deposition oxide coating method; the film colour is formed by electrochemical oxidation in a specific solution.
(4) High-temperature oxide implantation; this is the process of immersing the workpiece in a specific molten salt and holding it at a certain process parameter, so that the workpiece will form an oxide film of a certain thickness, which will take on a variety of different hues.
(5) Pyrolytic Colour Separation: more complex and less commonly used in the industry.