Effect Of Chromium On Austenitic Stainless Steel

Chromium is the most important alloying element in austenitic stainless steel. The rust and corrosion resistance of austenitic stainless steel is mainly due to the fact that chromium promotes the passivation of the steel and keeps the steel in a stable passivation state under the action of corrosion. the result of.

The influence of chromium on the structure: In austenitic stainless steel, chromium is an element that strongly forms and stabilizes iron, reducing the austenite region. As the content in the steel increases, ferrite ( δ) structure, research shows that in chromium-nickel austenitic stainless steel, when the carbon content is 0.1% and the chromium content is 18%, in order to obtain a stable single austenite structure, the required nickel content is the lowest, about 8% In this regard, the commonly used 18Cr-8Ni type chromium-nickel austenitic stainless steel is the most suitable one containing chromium and nickel. 

In austenitic stainless steel, with the increase of chromium content, the formation tendency of some intermetallic phases (such as delta phase) increases. When the steel contains molybdenum, the chromium content will increase and the formation of χ equal, as before As mentioned, the precipitation of σ and χ phases not only significantly reduces the ductility and toughness of steel, but also reduces the corrosion resistance of steel under some conditions. ) decreases, thereby improving the stability of the austenite matrix. 

Therefore, high-chromium (such as more than 20%) austenitic stainless steel is difficult to obtain martensitic structure even after cold working and low temperature treatment.