What Is Duplex Stainless Steel？

What is duplex stainless steel?

Duplex stainless steel has developed into the third generation since its birth in the United States in the 1940s. Its main feature is that the yield strength can reach 400-550MPa, which is twice that of ordinary stainless steel, so it can save materials and reduce equipment manufacturing costs. In terms of corrosion resistance, especially in harsh medium environments (such as seawater, high chloride ion content), the resistance to pitting corrosion, crevice corrosion, stress corrosion and corrosion fatigue of duplex stainless steel is significantly better than that of ordinary austenite. Stainless steel, comparable to high-alloy austenitic stainless steel.

Duplex Stainless Steel (DSS) refers to stainless steel with ferrite and austenite each accounting for about 50%. Generally, the content of the smaller phase needs to be at least 30%. In the case of low C content, the Cr content is 18%~28% and the Ni content is 3%~10%. Some steels also contain alloying elements such as Mo, Cu, Nb, Ti, and N.
This type of steel has the characteristics of both austenitic and ferritic stainless steel. Compared with ferrite, it has higher plasticity and toughness, no room temperature brittleness, significantly improved intergranular corrosion resistance and welding performance, while maintaining iron content. The solid stainless steel is brittle at 475°C, has high thermal conductivity, and has superplasticity and other characteristics. Compared with austenitic stainless steel, it has high strength and significantly improved resistance to intergranular corrosion and chloride stress corrosion. Duplex stainless steel has excellent pitting corrosion resistance and is also a nickel-saving stainless steel.