Super stainless steels, nickel-based alloy
What is super stainless steel? First of all, it is different from ordinary stainless steel in chemical composition. It refers to a high alloy stainless steel containing high nickel, high chromium and high molybdenum.
According to the microstructure characteristics of stainless steel, super stainless steel is divided into super ferritic stainless steel, super austenitic stainless steel, super martensitic stainless steel and super duplex stainless steel.
Super austenitic stainless steel is based on 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 caused by intergranular corrosion, and obtaining good mechanical properties, process properties and local resistance Corrosive performance and replaces Ti stabilized stainless steel.
Super ferritic stainless steel inherits the characteristics of ordinary ferritic stainless steel, such as high strength, good oxidation resistance, and excellent stress corrosion resistance. At the same time, it improves the ductility of the ferritic stainless steel-brittle transition, sensitivity to intergranular corrosion, and weld state. Limitations such as low toughness.
Using refining technology, reducing C and N content, adding stabilizing and weld metal toughening elements, can obtain high Cr, Mo and ultra-low C, N super ferritic stainless steel, making ferritic stainless steel resistant to corrosion and resistance Application of chloride pitting and crevice corrosion has entered a new stage.
It is characterized by low C content, high Mo and high N content, and the ferrite phase content in steel accounts for 40%. % ～ 45%, with excellent corrosion resistance.
Super martensitic stainless steel is a hardenable stainless steel with high hardness, strength and wear resistance, but poor toughness and weldability.
Ordinary martensitic stainless steel lacks sufficient ductility, it is very sensitive to stress during deformation, and cold forming is more difficult. By reducing the carbon content and increasing the nickel content, a 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 a number of different applications of super martensitic steels have been developed.
Super martensitic steel has been widely used in oil and gas extraction, storage and transportation equipment, hydroelectric power generation, chemical and high temperature pulp production equipment.
Applications of Super stainless steel:
- 1. Ocean: marine structures in the sea environment, desalination, seawater aquaculture, seawater heat exchange, etc.
- 2. Environmental protection field: flue gas desulfurization equipment for thermal power generation, wastewater treatment, etc.
- 3. Energy field: atomic power generation, comprehensive utilization of coal, sea tide power generation, etc.
- 4. Petrochemical industry: oil refining, chemical and chemical equipment, etc.
- 5. Food field: salt making, soy sauce brewing, etc.