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What Is The 2205 Material

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Duplex stainless steel (UNS S31803, S32205, S32750, S32900) combines the advantages of Ferrite and Austenite steel. Its duplex structure is conducive to obtaining high strength and stress resistance. In addition, higher content of chromium, nitrogen and molybdenum increases corrosion performance and duplex steel also has good welding performance. Due to its excellent properties, duplex stainless steel is widely used in chemical industry, paper manufacturing, desalination equipment, firewalls, Bridges, pressure vessels, heat exchangers, turbine blades and transmission shafts of offshore systems.

Sometimes, UNS S31803 and UNS S32205 are referred to as duplex 2205. Generally, UNS2205 contains ASTM S31803 and S32205 duplex stainless steels. In other words, S31803 and S32205 are both called 2205 stainless steel, and S32205 is the upgraded series of S31803 by the adding of the lower limit content of Cr, Mo and N elements, which makes the little difference in mechanical properties. Their tiny differences in chemical elements and physical properties are showed below:

UNS2205 C max P S Si max Mn max N Mo Ni Cr
S31803  0.03  0.03 0.02 1.00  2.00 0.08-0.2 2.5-3.5 4.5-6.5 21.0-23.0
S32205  0.03max 0.03 0.02 1.00max 2.00 max 0.14-0.2 3.0-3.5 4.5-6.5 22.0-23.0
UNS2205 Tensile strengthmin, Mpa Yield strength0.2% offset, min, Mpa Elongation, A5%
S31803 620 450 25
S32205 655 450 25

According to the ASTM A182 Standard, Specification for forged or stainless steel pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service, UNS S31803 and UNS S32205 cannot be confused and they specified in different number, S31803 is marked by F51 and S32205 is F60.

When speaking of 2205 steel, it generally refers to S31803 or F51, while UNS S32205 or F60 conforms to ASTM 2205 adopts its higher corrosion resistance range, that is, UNS S32205 requires higher Chromium and Nitrogen content, thus guaranteeing better corrosion resistance. Generally, S32205 steel plate and S31803 are also called double standard steel plate, or 2205 steel plate for short. Our factory produce 2205 tubing and 2205 plates to make its chemical composition conform to two specifications of UNS 31803 and S30025. Our steel plate in stock can meet two kinds of standards at the same time.

 

 

Mechanical properties of 2205 duplex

2205 (UNS S32305) is a nitrogen-alloyed duplex stainless steel, with a chemical composition containing 22-23% chromium, 3-3.5% molybdenum, and 4.5-6.5% nickel.   The high chromium and molybdenum content provide good corrosion resistance, and the overall combination allows this alloy to be stronger and tougher than most standard austenitic steels. 2205 duplex stainless steels maintains good weldability in their thickest sections, and they are much more resistant to chloride stress corrosion cracking and pitting than standard austenitic steels like 316L or 317L. 

With nearly twice the yield strength of other comparable austenitic grades, 2205 duplex steel products can withstand higher pressures and more corrosive environments with less material, saving on weight and fabrication costs.  This makes them ideal for chemical processing and storage pressure vessels and tanks, or high chloride environments for marine applications.

United Performance Metals stocks 2205 duplex stainless steel plate in thicknesses from 0.125″ to 1.000″, with FirstCut+ Processing services available. 

Heat Treatment and Heat Resistance

Similar to other duplex stainless steels, this grade of material can suffer from hydrogen embrittlement at temperatures over 300C.  To solve this issue, 2205 duplex steel plate should be solution annealed at 1900°F (1038°C) minimum up to 2012°F (1100°C), followed by a water quenching for rapid cooling. While it can be work hardened, thermal treatments will not harden this grade of stainless steel.

Machining and Weldability

The high strength of duplex 2205 makes it difficult to machine. Strong, rigid machines with low vibration are recommended, and carbide tooling will require lower feed speeds. 2205 plate is easily welded, but care should be taken to use appropriate filler materials (such as 2209, which is over-alloyed with additional nickel) to prevent excess ferrite formation.

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