What material is special stainless steel? What special stainless steels are there?

What material is special stainless steel? What special stainless steels are there?


 

What material is special stainless steel?
1. What is special stainless steel?
Super stainless steel, nickel-based alloy is a special type of stainless steel. First of all, it is different from ordinary stainless steel 304 in chemical composition. It refers to a high-alloy stainless steel containing high nickel, high chromium, and high molybdenum. Secondly, in terms of high temperature resistance or corrosion resistance, compared with 304, it has better high temperature resistance or corrosion resistance and is irreplaceable. In addition, from the classification of stainless steel, the metallographic structure of special stainless steel is a stable austenite metallographic structure. ​
2. Representative types of special stainless steel
1. Super austenitic stainless steel
On the basis of ordinary austenitic stainless steel, by improving the purity of the alloy, increasing the number of beneficial elements, reducing the C content, preventing the precipitation of Cr23C6 causing intergranular corrosion, we can obtain good mechanical properties, process performance and local corrosion resistance, and replace Ti stabilized stainless steel. ​
2. Super ferritic stainless steel
It inherits the characteristics of ordinary ferritic stainless steel such as high strength, good oxidation resistance, and excellent stress corrosion resistance, while improving the limitations of ferritic stainless steel such as ductility-brittleness transition, sensitivity to intergranular corrosion, and low toughness in the welded state. . Using refining technology to reduce the C and N content and add stabilizing and weld metal toughening elements, super ferritic stainless steel with high Cr and Mo and ultra-low C and N can be obtained, making ferritic stainless steel more resistant to corrosion and corrosion resistance. Applications such as pitting and crevice corrosion of chlorides have entered a new stage. ​
3. Super duplex stainless steel
This type of steel was developed in the late 1980s. The main grades include SAF2507, UR52N, Zeron100, etc. It is characterized by low C content, high Mo and high N content, and the ferrite phase content in the steel accounts for 40% to 45%. , has excellent corrosion resistance. ​
4. Super martensitic stainless steel
It is a hardenable stainless steel with high hardness, strength and wear resistance, but poor toughness and weldability. Ordinary martensitic stainless steel lacks sufficient ductility and is very sensitive to stress during deformation, making cold working difficult. By reducing the carbon content and increasing the nickel content, super martensitic stainless steel can be obtained. In recent years, various countries have invested heavily in the development of low-carbon and low-nitrogen super martensitic steels, and have developed a number of super martensitic steels for different uses. Super martensitic steel has been widely used in oil and gas extraction, storage and transportation equipment, hydropower, chemical industry and high-temperature pulp production equipment.