Duplex stainless steel

Duplex stainless steel has the characteristics of austenitic stainless steel and ferritic stainless steel because it has austenite + ferrite dual phase structure and the content of the two phase structures is basically the same. The yield strength can reach 400Mpa ~ 550MPa, which is twice that of ordinary austenitic stainless steel. Compared with ferritic stainless steel, duplex stainless steel has high toughness, low brittle transition temperature, significantly improved intergranular corrosion resistance and welding performance; while retaining some characteristics of ferritic stainless steel, such as 475 ℃ brittleness, heat High conductivity, small linear expansion coefficient, superplasticity and magnetic properties. Compared with austenitic stainless steel, duplex stainless steel has higher strength, especially the yield strength is significantly improved, and the pitting corrosion resistance, stress corrosion resistance, corrosion fatigue resistance and other properties have also improved significantly.

Duplex stainless steels are classified into four types: Cr18, Cr23 (excluding Mo), Cr22 and Cr25 based on their chemical composition. As for Cr25 duplex stainless steel, it can be divided into ordinary and super duplex stainless steel. Among them, Cr22 and Cr25 are more commonly used. Most of the duplex stainless steels used in China are produced in Sweden. The specific grades are: 3RE60 (Cr18 type), SAF2304 (Cr23 type), SAF2205 (Cr22 type), and SAF2507 (Cr25 type).