There are many forms of surface film that are damaged. Commonly there are the following:
Stainless steel is formed on the surface of a thin and strong and stable chromium-rich oxide film (protective film), to prevent the continued penetration of oxygen atoms, continue to oxidize, and get the ability to resist corrosion. Once for some reason, this kind of film is destroyed constantly, the oxygen atom in air or liquid will continue to infiltrate or the iron atom in metal will continue to separate out, form the loose iron oxide, the metal surface will be rusted constantly. There are many forms of this type of surface film that are damaged. The following are common: flanges
The surface of stainless steel contains deposits of dust or other dissimilar metal particles containing other metal elements. In humid air, the condensate between the deposit and stainless steel connects the two into a microbattery and initiates an electrochemical reaction. The protective film is damaged, which is called electrochemical corrosion.
The surface of stainless steel adheres to the organic matter juice (such as vegetables, noodles, soup, etc.). In the presence of water and oxygen, organic acids are formed, and organic acids attack the metal surface for a long time. pipe spooling
The surface of stainless steel adheres with acids, alkalis and salts (such as alkaline water on the wall of the decoration, lime water splashes), causing localized corrosion.
In contaminated air (such as an atmosphere containing a large amount of sulfides, carbon oxides, and nitrogen oxides), condensed water is formed and sulfuric acid, nitric acid, and acetic acid liquids are formed, causing chemical corrosion.