The main component of stainless steel is Cr (chromium), only when Cr content reaches a certain value, steel corrosion resistance.Therefore, stainless steel Cr (Cr) content is at least 10.5%.
The stainless steel also contains Ni, Ti, Mn, N, Nb, Mo, Si, Cu and other elements.The corrosion resistance of rust steel decreases with the increase of carbon content, therefore, the carbon content of most stainless steel is low, the maximum is not more than 1.2%, some steel Ω C (carbon content) even less than 0.03% (such as 00Cr12).
Chromium is the most important alloying element in austenitic stainless steels. The rust resistance and corrosion resistance of austenitic stainless steels are mainly due to the fact that chromium promotes the passivation of the steel and keeps the steel stable and blunt under the action of iron.
In austenitic stainless steels, chromium is an element that strongly forms and stabilizes ferrite and reduces the austenitic region. With the increase of content in the steel, ferrite (δ) structure can appear in the austenitic stainless steels.
The research shows that in the Cr-Ni austenitic stainless steel, when the carbon content is 0.1% and the chromium content is 18%, in order to obtain a stable single austenitic structure, the nickel content is the lowest, about 8%. On this point, the commonly used 18Cr-8Ni type Cr-Ni austenitic stainless steel is the most suitable ratio of chromium and nickel.