About plate material

Stainless steel: refers to steel that is resistant to weakly corrosive media such as air, steam, water, and chemically aggressive media such as acids, alkalis, and salts. It is also known as stainless acid-resistant steel. In practical applications, steel that is resistant to weakly corrosive media is often called stainless steel, and steel that is resistant to chemical media is called acid-resistant steel. There is a certain difference in chemical composition between the two, the former is not necessarily resistant to chemical media corrosion, while the latter are generally stainless. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel.

Corrosion resistance mechanism: Chromium is the basic element for stainless steel to obtain corrosion resistance. When the chromium content in the steel reaches about 12%, chromium interacts with the oxygen in the corrosion medium to form a thin oxide film on the steel surface (from Passivation film Cr2O3), very difficult to dissolve in water, can further prevent the corrosion of oxygen and iron. Similarly, destroying the passive film Cr2O3 means destroying its ability to resist oxygen corrosion.

In addition, the halogen elements in the corrosive medium (such as the common chloride ions in water) can also replace Cr under certain conditions, so stainless steel will also rust under certain conditions, and will also be affected by media containing acids, alkalis, and salts corrosion,. Therefore, the corrosion resistance of stainless steel changes with the chemical composition of the steel itself, the mutual state, the use conditions and the type of environmental medium. The corrosion of stainless steel in water is mainly caused by chloride ion in water.

The remaining added elements in stainless steel also play different roles. Like Mo will offset the corrosion caused by chloride ion to a certain extent, but there is also a scope of application.