What is super austenitic stainless steel? What is nickel-based alloy?
What is super austenitic stainless steel? What is nickel-based alloy?
Super stainless steel and nickel-based alloy are a special type of stainless steel. They are significantly different from ordinary stainless steel in chemical composition, and their main feature is that they contain a high proportion of nickel, chromium and molybdenum. The most famous of these stainless steels is the steel containing 6% molybdenum (such as 254SMo). This steel has excellent local corrosion resistance, especially in seawater, oxidizing environment, crevice existence and low-speed scouring conditions. It shows good pitting resistance (PI ≥ 40) and stress corrosion resistance, and can be used as a substitute for nickel-based alloys and titanium alloys.
In addition, this special stainless steel performs well in high temperature resistance and corrosion resistance, which is better than 304 stainless steel. From the perspective of metallographic structure classification, they have a stable austenitic metallographic structure. Since this type of stainless steel is a high-alloy material, the manufacturing process is quite complicated and usually relies on traditional processes such as casting, forging, rolling, etc.
This special stainless steel plays an important role in many fields, such as:
Marine field: used for marine structures, seawater desalination, seawater aquaculture, seawater heat exchange, etc.
Environmental protection field: used for flue gas desulfurization devices for thermal power generation, wastewater treatment, etc.
Energy field: used for atomic power generation, comprehensive utilization of coal, tidal power generation, etc.
Petrochemical field: used for oil refining, chemical industry equipment, etc.
Food field: used for salt making, soy sauce brewing, etc.
In these special fields, ordinary 304 stainless steel often cannot meet the requirements. Therefore, special stainless steel is indispensable and cannot be replaced in these environments. With the rapid development of the economy and the increase in demand in the industrial field, the demand for higher-level stainless steel-special stainless steel (super stainless steel, nickel-based alloy) is increasing.
Representative special stainless steels include:
Super stainless steel: contains about 6% molybdenum, such as 254SMo, the main components are 25Ni-23Cr-5.5Mo-0.2N.
Incoloy series alloys: such as Incoloy800, the main components are 32Ni-21Cr-Ti, Al.
Inconel series alloys: such as Inconel600, the main components are 73Ni-15Cr-Ti, Al.
Hastelloy: such as C-276, the main components are 59Ni-15Cr-16Mo-4W.
Monel alloy: such as Monel 400, the main components are 65Ni-32Cu.
