Why do stainless steel materials still rust?

- Jun 11, 2020-

"stainless steel is not rusty, rust is not stainless steel, it may be a problem with steel."---most people think.

6.11 珍珠

 In fact, this is a one-sided misconception about the lack of understanding of stainless steel. Stainless steel will also rust under certain conditions. Stainless steel has the ability to resist atmospheric oxidation-that is, stainless, but also has the ability to corrode in the medium containing acid, alkali, salt-that is, corrosion resistance. However, the size of its anti-corrosion ability changes with the chemical composition of the steel itself, the mutual state, the use conditions and the type of environmental medium. Such as 440c steel pipe, it has absolutely excellent anti-corrosion ability in the dry and clean atmosphere, but it will soon be rusted in the  foggy atmersphere with a lot of salt by seaside area. Therefore, not every kind of stainless steel can resist corrosion in any environment.

 Stainless steel is based on an extremely thin, solid, dense and stable chromium-rich oxide film (protective film) formed on its surface, which prevents the infiltration and oxidation of oxygen atoms from continuing to obtain the ability to resist rust. Once for some reason, this kind of film has been continuously destroyed, the oxygen atoms in the air or liquid will continue to infiltrate or the iron atoms in the metal will continue to separate out, forming loose iron oxide, and the metal surface will be continuously rusted. 

To ensure that the metal surface keep bright permanently and not been rusted, ZFB recommends:

1. Remove attachments and Clean the surface of the decorative stainless steel to eliminate external factors that cause modification.

2. Using the stainless steel 316 material in the seaside area in case of  seawater corrosion.