What are the types of super stainless steel?

From the perspective of the microstructural characteristics of stainless steel, super stainless steel mainly includes super ferritic stainless steel, super austenitic stainless steel, super martensitic stainless steel and super duplex stainless steel.
Among them, super austenitic stainless steel is based on ordinary austenitic stainless steel. It has improved the alloy degree, enhanced the content of beneficial elements such as chromium and molybdenum, reduced the carbon content, avoided the precipitation of Cr23C6 and caused intergranular corrosion, and achieved excellent mechanical properties. Process performance and partial corrosion resistance, and replaces titanium elements to stabilize stainless steel.
Super ferritic stainless steel inherits the characteristics of high strength, high oxidation resistance, and excellent stress corrosion resistance of ordinary ferritic stainless steel, and also optimizes the ductility-brittleness transition of ferritic stainless steel and is more resistant to intergranular corrosion. Limitations such as sensitivity and low toughness in the welded state. Using refining technology to reduce the carbon and nitrogen content, and adding stabilizing and weld metal toughening elements, super ferritic stainless steel with higher chromium, molybdenum and ultra-low carbon and nitrogen can be obtained, making ferritic stainless steel more durable. Applications such as corrosion, chloride pitting corrosion and crevice corrosion have reached new heights.
Super duplex stainless steel was developed in the late 1980s. Common grades are mainly SAF2507, UR52N, Zeron100, etc. It is characterized by relatively low carbon content, but high content of molybdenum and high nitrogen, of which the ferrite phase content accounts for 40%-45%, with good corrosion resistance.
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 has insufficient ductility, is very sensitive to stress during deformation, and is difficult to cold work. By reducing the carbon content and increasing the nickel content, super martensitic stainless steel can be obtained.
Nitrogen alloyed stainless steel. Nitrogen is added to stainless steel as an alloying element, which can effectively enhance the stability of the austenite structure, balance the proportion of phases in duplex steel, and enhance the strength and corrosion resistance of stainless steel without affecting the plasticity and toughness of stainless steel. properties and can partially replace nickel in stainless steel. In duplex stainless steel, nitrogen delays the dispersion and precipitation of intermetallic compounds; in martensitic stainless steel, nitrogen and other elements generate nitrides distributed on the grain boundaries, which can enhance the hardening ability and avoid austenite and iron during high-temperature tempering. The growth of body grains. The high-nitrogen-content austenitic stainless steel produced in recent years is not only high-strength non-magnetic austenitic stainless steel, but also has good high-temperature strength. It is widely used as low-temperature superconducting materials, high corrosion resistance and non-magnetic materials.