Stainless steel products have the ability to resist atmospheric oxidation-non-corrosion, but also have the ability to corrode in media containing acid, alkali and salt-that is, corrosion resistance.
However, the scale of its corrosion resistance will vary depending on the chemical composition of different steels, the state of mutually added elements, the conditions of use, and the types of environmental media.
For example, stainless steel 304 wire, which has absolutely excellent anti-corrosion ability in a dry and clean atmosphere, but when moved to the sea, its surface oxidation resistance can be significantly weakened in the sea fog containing a lot of salt; while 316 wire The performance is good. Therefore, it is not any kind of stainless steel that is corrosion-resistant and does not rust in any environment.
Stainless steel thin products rely on the extremely strong, dense and stable chromium-rich film (protective film) formed on the surface to prevent oxygen atoms from continuing to penetrate and continue to oxidize, thereby obtaining rust resistance.
For some reason, the oxygen atoms in the air or liquid will continue to infiltrate or the iron atoms in the metal will continue to precipitate out, forming loose iron oxide, and the metal surface will continue to be corroded.
There are many forms of damage to the surface film, and the common ones in daily life are as follows:
1.) There are dust or other foreign metal particles attached to the surface of the stainless steel.
Whenever in humid air, the condensed water between the stainless steel connects the two into a micro battery, triggering an electrochemical reaction and destroying the protective film, which is called electrochemical corrosion.
2.) Organic juice (such as winter melon, vegetables, noodle soup, sputum, etc.) adheres to the surface of stainless steel and forms organic acid in the presence of water and oxygen. Organic acids will surely corrode metal surfaces for a long time.
3.) The surface of stainless steel adheres to acid, alkali, and salt substances (such as alkaline water and stone gray water splashing on the decoration wall), causing local corrosion.
4. In the polluted air (such as an atmosphere containing a large amount of sulfide, carbon oxide, nitrogen oxide), contact with condensed water, thereby forming liquid spots such as sulfuric acid, nitric acid, acetic acid, and causing chemical corrosion.
All of the above conditions will cause damage and rust of the protective film on the surface of the stainless steel. Therefore, in order to ensure that the stainless steel metal surface is permanently bright and not corroded, we make recommendations:
1. The surface of decorative stainless steel must be cleaned and scrubbed frequently in order to remove attachments and eliminate external factors that cause deterioration.
2. Type 316 stainless steel should be used in areas close to the coast, which can effectively resist seawater corrosion.