Stainless steel grade SS-920 (UNS S92020) is a duplex stainless steel with a microstructure that typically consists of around 50% austenite and 50% ferrite. It is characterized by its high strength and excellent resistance to stress corrosion cracking in chloride solutions. The steel was developed to bridge the performance gap between austenitic and ferritic grades of stainless steel and has a higher yield strength than both its ferritic and austenitic counterparts.
The engineered microstructure of SS-920 gives it higher mechanical properties than other grades of stainless steel, making it suitable for applications where high strength and good corrosion resistance are required. It is especially able to withstand corrosive environments such as those found in seawater, making it a popular choice for applications in the marine industry.
This grade has excellent weldability, and can be joined to itself, other austenitic grades, and ferritic grades. It is also a relatively inexpensive grade, making it an attractive option for many applications.
Physical Properties of SS-920:
Density: 7.79 g/cm³
Tensile Strength: 700 MPa (min)
Yield Strength: 460 MPa (min)
Elongation: 21% (min)
Modulus of Elasticity: 193 GPa
Thermal Conductivity: 16 W/mK
Thermal Expansion: 9.3 μm/m °C
Hardness: 42 HRC (max)
Corrosion Resistance: Excellent in both oxidizing and reducing environments, includes a wide range of media including chloride solutions and seawater.
Machinability: SS-920 is a somewhat difficult stainless steel grade to machine because of its extraordinary strength and toughness. It is possible, but it may require special tools and cutting parameters.
Formability: SS-920 can be formed with relative ease, but is limited by its high yield strength. The grade is better suited to forming processes than ferritic grades, but is not as formable as austenitic grades due to its higher strength.
Weldability: SS-920 has excellent weldability and can be joined to itself, austenitic, and ferritic stainless steel grades. It is often used for welding dissimilar joint pairs in applications where corrosion and strength are equally important.
Applications:
Due to its combination of properties, SS-920 is increasingly popular for a wide range of industrial applications. Some of the most common applications for this grade of stainless steel include:
Marine: SS-920 is highly resistant to seawater corrosion and is used for equipment and components in marine industries.
Oil and Gas: This grade is used throughout the oil and gas industry for valves, pumps, and other components which require high strength and good corrosion resistance.
Aerospace: SS-920 is also used in aerospace applications for components which need to withstand the rigors of high temperatures and pressures.
Chemical Processing: Due to its excellent corrosion resistance, SS-920 is used in a wide range of chemical processing applications. It is also used in desalination plants, pulp and paper applications, and other industrial processes.
Conclusion
Stainless steel grade SS-920 (UNS S92020) balances properties including strength, corrosion resistance, machinability, formability, weldability, and cost. It has a higher yield strength than both its ferritic and austenitic counterparts, and its excellent corrosion resistance makes it a popular choice for use in marine and chemical processing applications. The steel is relatively inexpensive and is increasingly being used for a wide range of industrial applications.
