Why does stainless steel wire rust?

Why does stainless steel wire rust? When brown rust spots appear on the surface of stainless steel, people are surprised: "Stainless steel does not rust, and it is not stainless steel if it rusts, and there may be a problem with the steel." In fact, this It is a one-sided misconception about the lack of understanding of stainless steel wire. Stainless steel rods 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 corrode in media containing acids and alkali salts—that is, corrosion resistance. However, the size of its anti-corrosion ability varies with the chemical composition of the steel itself, the additive state, the use conditions and the type of environmental media. For example, 304 steel has absolutely excellent anti-corrosion ability in a dry and clean atmosphere, but Move it to a seaside area, in the salty sea fog, it will rust quickly, and the 316 steel will do just fine. Therefore, it is not any kind of stainless steel that can resist corrosion and rust in any environment. stainless steel wire factory

 Stainless steel is a layer of extremely dense, firm and stable chromium-rich oxide film (protective film) formed on its surface to prevent the continuous infiltration and oxidation of oxygen atoms to obtain the ability to resist rust. Once the film is damaged continuously 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, the most common in daily life are the following:

1. On the surface of stainless steel, there are deposits of dust or heterogeneous metal particles containing other metal elements. In humid air, the condensed water between the deposits and the stainless steel connects the two into a micro-battery, which triggers an electrochemical reaction. , the protective film is damaged, called electrochemical corrosion.

2. The surface of stainless steel adheres to organic juices (such as vegetables, noodle soup, sputum, etc.), which constitute organic acids in the presence of water and oxygen, and organic acids will corrode the metal surface for a long time.

3. The surface of stainless steel adheres to substances containing acids, alkalis and salts (such as alkali water and lime water splashing from decoration walls), causing local corrosion.

4. In the polluted air (such as the atmosphere containing a large amount of sulfide, carbon oxide, nitrogen oxide), in case of condensed water, the formation of sulfuric acid, nitric acid, acetic acid liquid point, causing chemical corrosion.

The above conditions can cause damage to the protective film on the stainless steel surface and cause rust.

Therefore, to ensure that the metal surface is permanently bright and not rusted, we recommend:

1. The stainless steel surface must be cleaned and polished frequently to remove attachments and eliminate external factors that cause rust.

2. 316 stainless steel should be used in seaside areas, and 316 material can resist seawater corrosion.

3. The chemical composition of some stainless steels on the market cannot meet the corresponding national standards and cannot meet the 304 material requirements. Therefore, it will also cause rust, which requires users to carefully choose products from reputable manufacturers.