Both the advantages of austenitic and ferritic stainless steel, and has a superplastic. Austenite and ferrite each account for about half of the stainless steel. In the case of low C content, Cr content of 18% to 28%, Ni content of 3% to 10%. Some steel also contains Mo, Cu, Si, Nb, Ti, N and other alloying elements. This type of steel combines the characteristics of austenitic and ferritic stainless steel, compared with ferrite, ductility, toughness, no room temperature brittleness, resistance to intergranular corrosion and welding performance are significantly improved, while maintaining iron Fritility of 475 ℃ brittleness of stainless steel and high thermal conductivity, with superplasticity and so on. Compared with austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion resistance has improved significantly. Duplex stainless steel has excellent pitting corrosion resistance, but also a section of nickel stainless steel.