Why does stainless steel rust?

When the rusty steel surface appears brown rust spots, people will be surprised: "stainless steel will rust, rust is stainless steel, this may be a problem of steel quality." In fact, this is a misunderstanding of the lack of understanding of stainless steel. In some cases, stainless steel can also rust.

Stainless steel has the ability to resist atmospheric oxidation, that is, stainless steel, also has the ability to resist corrosion in the medium containing acid, alkali salt. However, its ability varies with the chemical composition of steel itself, mutual state, service conditions the type of environmental media. 304 material, for example, has excellent corrosion resistance in a dry clean atmosphere, but when it moves to the seaside area, it quickly rusts in sea fog containing a lot of salt. Therefore, it is any kind of stainless steel that can resist rusting at any time.

Stainless steel is based on a very thin, strong, dense stable chromium rich oxide film formed on its surface to prevent oxygen atoms penetrating oxidizing to obtain durability. Once the membrane is continuously destroyed for some reason, the oxygen atoms in the air liquid will continue to penetrate, the iron atoms in the metal will continue to separate to form loose iron oxide, the metal surface will be continuously damaged. Corrosion. This kind of surface film is damaged in many ways is often seen in daily life.

1. Dust other metal particles containing other metal elements will accumulate on the surface of stainless steel. In humid air, the condensate between the accessories the stainless steel connects them to form a miniature battery, which leads to a chemical reaction. Damage to the protective film is called electrochemical corrosion.

2. The organic juice adhered to the stainless steel surface. In the presence of water oxygen, it forms an organic acid corrodes the metal surface for a long time.

3. The surface of stainless steel contains acid, alkali salt, which will cause local corrosion.

4. In the polluted air, the condensate will form liquid spots of sulfuric acid, nitric acid acetic acid, which will cause chemical corrosion.

These conditions will lead to the destruction corrosion of the protective film on the surface of stainless steel. Therefore, in order to ensure that the metal surface is bright does rust, we recommend that:

① The surface of decorative stainless steel should be cleaned scrubbed frequently to remove the attachment eliminate the external factors causing rust.

② There are 201 202 stainless steels on the market, which are easy to rust in coastal areas are suitable for use in environments without industrial pollution air corrosion.

③ 304 stainless steel is used in the beach area to resist seawater corrosion.