Duplex 2205® Stainless Steel

UNS S31803/UNS S32205

UNS S31803 and UNS S32205 are commonly referred to as Duplex 2205® material, whose “Duplex” name is derived from the mixed microstructure which contains about equal portions of ferrite and austenite. Developed more than 70 years ago in Sweden precisely for the sulfite paper industry where the Duplex’s were used to combat corrosion problems caused by chloride-bearing cooling waters and other aggressive chemical products. Since then there have been advancements in the composition such as the deliberate addition of nitrogen as an alloying agent, which afterwards quickly made Duplex the “workhorse” of stainless steels. Generally, UNS S31803 has been solely designated to the Duplex 2205® grade. More recently, it has been available complying with the higher corrosion resistant composition UNS S32205. The only difference in the UNS numbers is that UNS S32205 contains a higher nitrogen content which guarantees better corrosion resistance. Composed of between 21% to 23% chromium, 4.5% to 6.5% nickel, 5% to 3.5% molybdenum, 2% manganese, and 1% silicon, with the balance being iron. Also found in Duplex Stainless Steel are trace amounts of carbon, phosphorus, sulfur and nitrogen.

Benefits of Duplex include: good weldability and workability, high resistance to corrosion fatigue, stress corrosion cracking (especially chloride stress corrosion cracking), erosion, and high energy absorption. Other advantages of Duplex are higher heat conductivity and low thermal expansion compared to austenitic stainless steels, high strength, good resistance to sulfide stress corrosion, and high resistance to pitting and crevice to corrosion. Duplex 2205® accounts for over 80% of the total usage of Duplex stainless steels throughout the world because of its superior workability as well as corrosion resistance.

 

Pipe – Seamless and Welded

Tubing – Seamless and Welded

Fittings – Butt Weld, Socket Weld

Flanges

½” Thru 12”

Schedules 10s, 40s, 80s and 160

Pressure Fittings - Threaded

1/4” Thru 2”

150#, 300#, 3000# and 6000#

Bar- Round, Flat and Hex

Plate and Sheet

Specifications

Pipe – ASTM/ASME A/SA 790 Seamless/Welded Tubing A789

Butt-Weld Fittings – ASTM/ASME A/SA815 Sheet/Plate A240

Flanges – ASTM/ASME A/SA 182 Bar A276

Pressure Fittings - A/SA 182, A/SA 479

 

 

Chemical Composition %

C	Cr	Fe	Mn	Mo	N	Ni	P	S	Si
Max			Max				Max	Max	Max
0.030	21.0-23.0	Bal	2.0	2.50-3.50	0.08-0.20	4.50-6.50	0.03	0.02	1.0

 

All information above is not guaranteed and not for design purposes