Duplex steel is resistant to rust and acids and offers higher strength than chromium-nickel steels with higher ductility and formability than stainless chromium steel.
Duplex steel has a two-phase structure consisting of ferrite and austenite. Significant properties of duplex steel are its high resistance to surface corrosion, local corrosion and stress corrosion cracking.
The structure of this steel is very strong against corrosion fatigue, energy absorption, erosion and abrasion, low thermal expansion and has good weldability.
Due to its high resistance to corrosion, duplex steel is mainly used in the chemical industry, the petrochemical industry, seawater desalination plants and offshore technology.
The cutting of duplex steel can be done very well by laser or plasma cutting machines. Shearing is not preferable due to the high forces needed for shearing.
- Milling and machining
Milled parts made of duplex steel can be produced in machining centres. The requirements for the tools are higher than for other types of steel.
With the exception of gas welding, duplex steel is suitable for all common welding processes.
The classification of duplex steel into different groups
These include, among others:
- Lean Duplex
Is not alloyed with molybdenum and is available in the steel grades 1.4482, 1.4162, 1.4062, 1.4362 and 1.4655
- Standard Duplex
Has excellent resistance to corrosion. This steel is designated 1.4462, duplex with 25% chromium is designated 1.4507.
- Super Duplex
Is available in the varieties 1.4410, 1.4501 and 1.4477 The very high corrosion resistance is achieved by adding molybdenum. Due to its high strength and chloride resistance, this steel grade is very well suited for offshore applications.