Some customers reported that the stainless steel crimping mesh screen also rusted, so they questioned whether the stainless steel material used was qualified, whether it was a fake product, and why stainless steel rusted? When brown rust spots (dots) appeared on the surface of stainless steel, people were surprised: they thought "stainless steel does not rust, rust is not stainless steel, there may be problems with the steel". In fact, this is a one-sided and wrong view of the lack of understanding of stainless steel screens. Stainless steel will also rust under certain conditions.
Stainless steel crimping mesh has the ability to resist atmospheric oxidation---that is, stainlessness, and also has the ability to corrode in media containing acids, alkalis, and salts---that is, corrosion resistance. However, the size of its corrosion resistance changes with the chemical composition of the steel itself, the state of mutual addition, the conditions of use and the type of environmental media. For example, 304 steel pipe has excellent corrosion resistance in dry and clean atmosphere, but it will soon rust when it is moved to the coastal area in sea fog containing a lot of salt; while 316 steel pipe performs well. Therefore, not all kinds of stainless steel can be rust-free in any environment.
Stainless steel crimped mesh relies on a thin, solid, dense and stable chromium-rich oxide film (protective film) formed on its surface to prevent the continued infiltration and oxidation of oxygen atoms, thereby obtaining the ability to resist rust. Once this film is continuously damaged for some reason, oxygen atoms in the air or liquid will continue to infiltrate or iron atoms in the metal will continue to separate out, forming loose iron oxide, and the metal surface will continue to rust. There are many forms of damage to this surface film, and the following are the most common in daily life:
1. The surface of the stainless steel crimped mesh accumulates dust containing other metal elements or attachments of heterogeneous metal particles. In humid air, the condensed water between the attachments and the stainless steel connects the two into a micro-battery, triggering an electrochemical reaction, and the protective film is damaged, which is called electrochemical corrosion.
2. Organic juice (such as vegetables, noodle soup, sputum, etc.) adheres to the surface of the stainless steel crimped mesh. In the presence of water and oxygen, it forms organic acid, which corrodes the metal surface for a long time.
3. The surface of stainless steel wire mesh contains acid, alkali and salt substances (such as alkaline water and lime water splashing from wall decoration), causing local corrosion.
4. In polluted air (such as atmosphere containing a large amount of sulfide, carbon oxide and nitrogen oxide), condensed water forms sulfuric acid, nitric acid and acetic acid liquid points, causing chemical corrosion.
The above situations can cause the destruction of the protective film on the surface of stainless steel and cause rust. Therefore, in order to make the metal surface bright and not corroded, we must clean and passivate it.
