Stainless steel square tube is a hollow long steel, because the section is square so called square tube. A large number of pipes used for conveying fluids, such as oil, natural gas, water, gas, steam, etc., in addition to bending, torsion strength of the same, the lighter weight, it is also widely used in the manufacture of mechanical parts and engineering structure.

Metal in the atmosphere can react with oxygen in the surface of the formation of oxide film, the formation of ordinary carbon steel iron oxide will continue to oxidize, so that corrosion continues to expand, and ultimately the formation of holes. This can be used to protect the carbon steel surface with paint or oxidation resistant metal, but this protective layer is only a film, if the protective layer is destroyed, the following steel will start to rust.

304 stainless steel square tube is corroded with the chromium content in steel, steel in the chromium content of 12%, in the atmosphere, the surface of the stainless steel tube to generate a passivation, dense chromium oxide and protect the surface, Can prevent further reoxidation. This oxide layer is extremely thin, through which it can see the natural gloss of the steel surface, so that stainless steel has a unique surface.

If the chrome film is destroyed, the chromium in the steel reacts with the oxygen in the atmosphere to produce a passivation film. In some special circumstances, stainless steel will also appear some local rot.