Why do stainless steel seamless pipes need surface treatment?

Why do stainless steel seamless pipes need surface treatment?

Stainless steel seamless pipe is a kind of hollow long round steel, which is mainly widely used in industrial pipelines and mechanical structural components such as petroleum, chemical industry, medical treatment, food, light industry, mechanical instrumentation and so on. In addition, when the bending and torsional strength are the same, the weight is lighter, so it is also widely used in the manufacture of mechanical parts and engineering structures. It is also commonly used as furniture and kitchen utensils.

Commonly used surface treatment technologies for stainless steel seamless pipes include the following treatment methods:
① Surface whitening treatment;
②Surface mirror bright treatment;
③Surface coloring treatment.

1. Natural color whitening treatment on the surface of stainless steel seamless pipes:
During the processing of stainless steel pipes, black oxide scale will be produced after coiling, edge sealing, welding or artificial surface heating. This hard gray-black oxide scale is mainly composed of two substances: EO4, NiCr2O4 and NiF. In the past, hydrofluoric acid and nitric acid were generally used to remove strong corrosion. However, this method is expensive, pollutes the environment, is harmful to the human body, and is highly corrosive, so it is gradually being eliminated.

There are two main methods of oxide scale treatment:
⑴Sand blasting (shot blasting) method: The method of spraying glass beads is mainly used to remove the black oxide scale on the surface.
(2) Chemical method: Use pollution-free pickling passivation paste and non-toxic cleaning solution containing inorganic additives to soak at room temperature. This achieves the purpose of whitening the natural color of stainless steel pipes. After processing, it basically looks matte.

2. Mirror-brightened stainless steel seamless pipe surface:
According to the different requirements of stainless steel pipes, mechanical polishing, chemical polishing, electrochemical polishing and other methods can be used to achieve mirror gloss.

3. Surface coloring treatment:
The coloring of stainless steel pipes not only gives stainless steel products a variety of colors, increases the variety of products, but also improves the wear resistance and corrosion resistance of the products.
The stainless steel coloring method is as follows:
(1) Chemical oxidation coloring method;
⑵Electrochemical oxidation coloring method;
(3) Ion deposition oxide coloring method;
⑷High temperature oxidation coloring method;
⑸Vapor phase pyrolysis coloring method.

Warm reminder: According to the production method, stainless steel pipes are divided into two categories: seamless pipes and welded pipes. Seamless steel pipes can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes and extruded pipes. Cold-drawn and cold-rolled pipes are secondary processing of steel pipes. Welded pipes are divided into straight seam welded pipes and spiral welded pipes.