Duplex Stainless Steel (Duplex Stainless Steel, referred to as DSS), refers to ferrite and austenite each accounted for about 50%, generally less phase content also needs to reach at least 30% of stainless steel. In the case of low C, the Cr content is 18% to 28%, and the Ni content is 3% to 10%. Some steels also contain Mo, Cu, Nb, Ti, N and other alloying elements. This kind of steel has the characteristics of austenitic and ferritic stainless steel, compared with ferritic, higher plasticity, toughness, no room temperature brittleness, intergranular corrosion resistance and welding performance are significantly improved, while also maintaining the ferritic stainless steel 475℃ brittleness and high thermal conductivity, with superplasticity and other characteristics.