Stainless steel is not to rust, but not easy to rust. Under some conditions, the stainless steel will also rust. The surface of stainless steel has a very thin, thin and stable chromium rich oxide film, stainless steel rust, by this oxide film to prevent oxygen atoms infiltration oxidation reaction and rust. In fact, some stainless steels have both rust resistance and acid resistance (corrosion resistance). The rust and corrosion resistance of stainless steel is due to the formation of a chromium-rich oxide film (passivation film) on its surface, which isolates the metal from the external medium, prevents the metal from being further corroded, and has the ability to repair itself. If it is damaged, the chromium in the steel will regenerate a passivation film with the oxygen in the medium and continue to play a protective role. When the oxide film is damaged, it rust easily.
1)The environment of stainless steel is humid, in the case of water and oxygen, the formation of organic acid and erosion damage to the surface of stainless steel.
2)Stainless steel products are mechanically damaged by the installation tools and then damage the surface protective film. For example, when the stainless steel bolts are installed in the outdoor curtain wall engineering, the wrench causes mechanical damage to the place where the bolt head contacts. After rain washing, the head of the stainless steel bolts will appear slight floating rust.
3)There are dust impurities or metal particles on the surface of stainless steel, which is easy to electrochemical react with stainless steel in humid air to accelerate the corrosion of stainless steel.
4) Stainless steel surface exposed to acid, alkali, salt and other substances are prone to chemical reaction corrosion. For example, the curtain wall connection fasteners in coastal cities are generally selected for 316 stainless steel products (more corrosion-resistant than 304 stainless steel), because the high salt content in the air of coastal cities is easy to cause corrosion to stainless steel.
Therefore, in order to make stainless steel products keep bright and not corroded, it is necessary to choose the right material of stainless steel products, followed by is to clean and maintain stainless steel products, remove surface impurities to avoid reaction and corrosion.
Post time: Aug-19-2022