Cr in CA6NM martensitic stainless steel

Cr – one of the major alloying elements in martensitic stainless steel CA6NM. It plays a decisive role in corrosion resistance.

The role of Cr in CA6NM martensitic stainless steel

Cr——one of the major alloying elements in martensitic stainless steel CA6NM. It plays a decisive role in corrosion resistance. With Cr in the steel, the corrosion resistance of stainless steel in the corrosive medium will increase. Cr can reduce the sensitivity of steel to pitting corrosion. There will improve pitting corrosion resistance when steels contain Mo at the same time. Also, Cr is a strong ferrite formation element. It can reduce the austenite phase in the phase diagram. The content of Cr in martensitic stainless steel is generally between 10.5~18%.

Cr is a typical ferrite formation element. Excessive Cr can promote δ ferrite formation. Therefore after solution treatment, it will not get full martensite. There is part of the delta ferrite. Thereby it’ll affect the steel toughness and stress corrosion resistance. Therefore, the Cr content of super martensitic stainless steel should be controlled between 12% and 13%.