Characteristics of duplex stainless steel

Duplex stainless steel is a type of stainless steel consisting of a ferrite phase and an austenite phase. It complements the stress corrosion cracking resistance, which is the weakness of austenitic stainless steels, and ferritic stainless steels. Super Duplex Sheet has excellent performance. For this reason, the application is expanding to various fields, such as the petrochemical industry, chemical tankers, and offshore structures to bridges. Below are some of advantage and features of Duplex 2205 Sheet.

Also called a dual-phase alloy, it is a stainless steel material in which an austenite structure and a ferrite structure coexist. The greatest feature of the two-phase system is that it is resistant to stress corrosion cracking. It has magnetism because it has a ferrite structure. The coefficient of thermal expansion is between that of ferrite and austenite. Ductility is a property that is similar to ferrite and is said to have high strength, high corrosion resistance, and is economical. It is used in chemical plants, water tanks, reservoirs, oil well pipes, chemical tankers, etc. If the amount of N added is small, the toughness of the welded part and the corrosion resistance will become a problem.

Characteristics of duplex stainless steel

The microstructure of duplex stainless steel is a fine dispersion of austenite phase in the ferrite matrix, and the ratio of both phases is approximately 1:1 in the solution heat treatment state. This state is the most stable in terms of microstructure, and is capable of exerting the strength of duplex stainless steel. Super Duplex 2507 Sheet has the following characteristics compared to common austenitic stainless steels.

1. High strength thin and lightweight design with the strength that is almost twice that of SUS304 and SUS316 (0.2% proof stress comparison) is possible.
2. Pitting corrosion resistance of Ferralium 255 Plate has better stress corrosion cracking resistance than general-purpose austenitic steel and good pitting corrosion resistance.
3. Price stability. Since UNS S32750 Plate contains less nickel and molybdenum than general-purpose austenitic steel, that why there is almost no risk of fluctuations in raw material prices.

• Small thermal expansion coefficient and high thermal conductivity
• High room temperature strength
• Resistant to pitting corrosion and stress corrosion cracking

And advantages such as

• High nitrogen content
• Structural changes due to heat treatment are significant, and various properties such as corrosion resistance change

Main uses

• In Petrochemical plants, chemical tankers, environmental plants (flue gas desulfurization equipment, etc.)
• Duplex stainless steel is roughly classified into three grades of standard, super, and lean in terms of composition.
• Standard: A “standard” duplex stainless steel with a composition of 22%Cr-5%Ni-3%Mo-0.15%N.
• Super: Increase the room temperature strength and pitting corrosion resistance by increasing the content of Mo and N mainly from the standard.
• Lean: A company is working to reduce costs by reducing the Ni and Mo contents from the standard. By the way, "lean" means "thinned."

 There are also many other use of stain steels products in the iindrustry.