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Why does stainless steel rust?

Aug 20, 2018

People generally think stainless steel is not rusting, rusting is not stainless steel. In fact, this is a one-sided misunderstanding of stainless steel. Stainless steel will rust under certain conditions.

Stainless steels have the ability to resist oxidation in the atmosphere -- not to rust, but also to corrode in the medium containing acid, alkali and salt -- corrosion resistance. However, the corrosion resistance of the steel varies with the chemical composition of the steel, the state of adding, the conditions of use and the types of environmental media.

For example, 304 steel pipes, in the dry and clean atmosphere, have absolutely excellent anti-rust ability, but move it to the coastal area, in the sea fog with a lot of salt, it will soon rust. The 316 steel pipe performs well in this environment. Therefore, not any kind of stainless steel, in any environment can be resistant to corrosion, rust.

Stainless steel is formed by its surface of a very thin and strong and fine stable chrome oxide film (protective film), to prevent oxygen atoms continue to infiltrate, continue to oxidize, and obtain the ability to resist rust. If, for some reason, the film is constantly damaged, oxygen atoms in the air or liquid infiltrate or iron atoms in the metal are constantly separated to form loose iron oxide and the metal surface is constantly corroded.

Stainless Steel Stub End Suppliers

This kind of surface film is damaged in many forms, which are commonly seen in daily life:

1. There are particles of dust or other metal particles on the surface of Seamless Steel Reducer. In humid air, the condensed water between the particles and stainless steel connects them into a micro battery, causing an electrochemical reaction.

2. The stainless steel surface adheres to organic juice (such as melon, noodle soup, sputum, etc.), which constitutes organic acid in the presence of water and oxygen, and corrodes the metal surface with organic acid for a long time.

3. The adhesion of stainless steel surface contains acid, alkali and salt substances (such as alkaline water and limestone water spatter in the decoration wall), causing local corrosion.

4. In the polluted air (such as the atmosphere containing a large amount of sulfide, carbon dioxide and nitrogen oxide), the condensed water will form sulfuric acid, nitric acid and acetic acid liquid points, causing chemical corrosion.

To ensure that the metal surface is permanently shiny and not corroded, we should:

1) the surface of decorative stainless steel must be cleaned and scrubbed frequently to remove the attachments and eliminate external factors causing rust.

2) select stainless steel materials that conform to the surrounding environment; Materials such as 316 are resistant to seawater corrosion.

3) some of the chemical components of stainless steel tubes in the market do not meet the corresponding national standards and do not meet the material requirements. This requires careful selection of products from reputable Stainless Steel Stub End Suppliers.

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