Why stainless steel also rust?
1. Many people think that stainless steel tube will not rust, which is a wrong one-sided view. First of all, the stainless steel tube's rust and corrosion resistance is conditional. Stainless steel pipe is a steel pipe with no rust in the atmosphere, fresh water and other weak corrosive environment, and the chromium content in the steel must be ≥ 12 %. Rust will be rust if the chromium content is low or is not used in weak corrosive environments such as the atmosphere ( including although in weak corrosive environments such as the atmosphere, but cl - local enrichment conditions ). Acid - proof steel pipe is in the acid, alkali, salt and other strong corrosion medium corrosion of the steel pipe, but also under certain conditions corrosion resistance, such as medium type, temperature, concentration, impurity content, flow rate, pressure, and so on. The world does not rust under any conditions, corrosion - resistant stainless steel tubes.
2. The surface deposit and accumulation of stainless steel contain dust or attached materials with other metal elements. in moist air, the condensed water between the attached and stainless steel forms a tiny cell, which leads to electrochemical reaction and damage of the protective film, which is called electrochemical corrosion.
3. The stainless steel surface adhering to the organic juice ( such as vegetables and vegetables, soup phlegm, etc. ), in the presence of water and oxygen, constitutes an organic acid, and the formation of organic acid corrosion on the metal surface for a long time.
4. The surface adhesion of stainless steel contains acid, alkali and salt substances ( such as alkali water of decoration wall and whitewash test ) to cause local corrosion.
5. In the polluted air ( containing a large amount of sulfide, oxide and hydrogen oxide atmosphere ), in the case of condensed water, the formation of nitric acid and acetic acid solution, resulting in chemical corrosion.