Stainless steel is usually divided into martensitic steel, ferritic steel, austenitic steel, AUSTENITIC FERRITIC (duplex) stainless steel and precipitation hardening stainless steel according to its microstructure.
In addition, it can be divided into: chromium stainless steel, chromium nickel stainless steel and chromium manganese nitrogen stainless steel.
There are also special stainless steel plates and strips for pressure vessels (gb24511-2009).
The corrosion resistance of stainless steel decreases with the increase of carbon content.
Therefore, the carbon content of most stainless steels is low, not more than 1.2% at most, and the ω C (carbon content) of some steels is even lower than 0.03% (such as 00Cr12).
The main alloy element in stainless steel is Cr (chromium). Only when Cr content reaches a certain value, the steel has corrosion resistance.
Therefore, the general Cr (CR) content of stainless steel is at least 10.5%. Stainless steel also contains Ni, Ti, Mn, N, Nb, Mo, Si, Cu and other elements.