What to do if red stains appear on stainless steel plates
Date:2023-01-20View:349Tags:
Stainless steel will also rust under certain conditions. Stainless steel has the ability to resist atmospheric oxidation -- that is, rust resistance, and also has the ability to resist corrosion in media containing acids, alkalis, and salts -- that is, corrosion resistance However, the size of its anti-corrosion ability is changed with the chemical composition of the steel itself, the state of interaction, the use conditions and the type of environmental media. For example, 304 steel pipes have absolutely excellent anti-corrosion ability in a dry and clean atmosphere , but move it to the seaside area, in the sea fog containing a lot of salt, it will soon get rusty; while the 316 steel pipe performs well. Therefore, not any kind of stainless steel can resist corrosion in any environment, not rusty.
Stainless steel relies on an extremely thin, firm, dense and stable chromium-rich oxide film (protective film) formed on its surface to prevent oxygen atoms from continuing to infiltrate and oxidize, thereby obtaining the ability to resist corrosion. Once there is some reason, this If the film is continuously damaged, the oxygen atoms in the air or liquid will continuously infiltrate or the iron atoms in the metal will continuously separate out to form loose iron oxide, and the metal surface will be continuously rusted.
There are many forms of damage to this surface film, and the most common ones in daily life are as follows:
1. Dust containing other metal elements or attachments of heterogeneous metal particles accumulate on the surface of stainless steel. In humid air, the condensed water between the attachments and stainless steel connects the two into a micro-battery, triggering an electrochemical reaction , the protective film is damaged, which is called electrochemical corrosion.
2. Organic juices (such as vegetables, noodle soup, sputum, etc.) adhere to the surface of stainless steel. In the presence of water and oxygen, organic acids will be formed. For a long time, organic acids will corrode the metal surface.
3. The surface of stainless steel adheres to substances containing acids, alkalis, and salts (such as alkaline water and lime water splashed on the wall for decoration), causing local corrosion.
4. In polluted air (such as an atmosphere containing a large amount of sulfide, carbon oxide, and nitrogen oxide), when it encounters condensed water, it will form sulfuric acid, nitric acid, and acetic acid liquid points, causing chemical corrosion.
