Why do Stainless Steel Slides Rust?

Stainless steel slides generally adopt 304 stainless steel or 201 stainless steel to produce. Stainless steel material is characterized with corrosion resistance, oxidation resistance, high hardness, good ductility, and easy processing, etc, widely used in all walks of life. However, as time goes on, stainless steel will rust due to the environment around it caused, instead of quality problem!

Why do stainless steel slides still rust? Although stainless steel can withstand part of the acid, alkali and salt corrosion in dry air, and even can be rust-proof for general humidity in the air, it is easy to rust in coastal cities where there is a lot of salt fog in the air. The reason why stainless steels possess the ability to resist corrosion is the extremely thin, solid, fine and stable chromium-rich oxide film (protective film) formed on their surfaces. The film prevents oxygen atoms from constantly penetration and oxidation. Once the film is constantly destroyed for some reasons, oxygen atoms in the air or liquid will keep infiltrating or iron atoms in the metal will keep separating out, forming a loose iron oxide. Therefore, the metal surface will be endlessly corroded. There are many forms of destruction of the surface film:

1. The dust containing other metal elements or the attachment – heterogeneous metal particles deposits on the stainless steel surface. In the humid air, the attachment and the condensated water between stainless steel are connected into a micro-battery, triggering an electrochemical reaction, and the protective film is damaged, known as electrochemical corrosion.

2. The surface of stainless steel is adhered with organic sap (such as melon, vegetable, noodle soup, sputum, etc.) which forms organic acid in the presence of water and oxygen. The metal surface will be corroded if the acid exists for a long time.

3. The stainless steel surface contains acid, alkali and salt substances (such as alkaline water or lime water splashing on the decoration wall), causing localized corrosion.

4. In polluted air (such as the atmosphere containing a large number of sulfides, carbon monoxide, and nitric oxide), when encountering condensated water, sulfuric acid, nitric acid, and acetic acid liquid point is formed, and chemical corrosion happens.

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