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Duplex Stainless Steel
Multiple forms & standards.
At PM International, we’ve been working with Duplex stainless steel for decades because it hits that sweet spot of strength and corrosion resistance our clients count on. Whether you’re sourcing S31803 or S32205, we supply everything from welded and seamless pipe to custom-forged components. Duplex is a favorite for projects where standard stainless just won’t cut it — think offshore rigs, chemical facilities, and salt-heavy environments. Our team understands the nuances of these alloys and works closely with engineers to make sure the material fits the job — not just on paper, but in the field.
UNS S31803 – UNS S32205
- Duplex Plate/Sheet
- Duplex Seamless & Welded Tube
- Duplex Seamless & Welded Pipe
- Duplex Round Bar
- Duplex Flanges F51
- Duplex Specialty Forgings
- Duplex Seamless & Welded BW Fittings
| Trade Name | UNS | Duplex Industry Specifications | Chemical Composition (KSI) | Min.Tensile@ (KSI) | Min.Yield % | Elongation |
|---|---|---|---|---|---|---|
| SAF 2205® 22Cr | UNS S31803 | ASME SA-182 (F51), SA-240, SA-798, SA-790, SA-815 ASTM A182 (F51),A240, A276, A479, A789, A790, A815, A928, A988 SAE J405 | C 0.30 max Cr 21.0-23.0 Mn 2.00 max Mo 2.50-3.50 N 0.08-0.20 Ni 4.50-6.50 P 0.030 max S 0.020 max Si 1.00 max | 90 | 65 | 25 |
| SAF 2205® 22Cr | UNS S32205 | ASME SA-182 (F60), SA-240, SA-798, SA-790, SA-815 ASTM A182 (F60), A240, A276, A479, A480, A798, A790, A815, A928, A988 SAE J405 | C 0.30 max Cr 22.0-23.0 Mn 2.00 max Mo 3.00-3.50 N 0.14-0.20 Ni 4.50-6.50 P 0.030 max S 0.020 max Si 1.00 max | 95 | 65 | 25 |
General Duplex stainless steel information
The most widely used duplex (ferritic/austenitic) stainless steel grade is 2205 due to both its high strength and resistance to corrosion resistance. Over the years, the composition of duplex S31803 has been further refined, resulting in 1996 in the endorsement of restricted composition range Duplex UNS S32205. S32205 provides better corrosion resistance. In fact, much of the Duplex S31803 currently produced also complies with Duplex S32205. 2205 is not generally suitable for temperatures above 300ºC due to precipitation of brittle micro constituents, nor below -50ºC because of its ductile-to-brittle-transition.
Duplex Applications
- Chemical processing, transport and storage
- Oil and Gas exploration and processing equipment
- Marine and other high chloride environments
- Pulp and paper digesters, liquor tanks and paper machines
Duplex Corrosion Resistance
S32205 offers excellent general corrosion resistance and is superior to Grade 316 in most environments, providing excellent resistance to localized corrosion including intergranular, pitting and crevice corrosion. The CPT of S32205 is generally at least 35ºC with resistance to chloride stress corrosion cracking (SCC) at temperatures of up to about 150ºC. With better sea water resistance than Grade 316, S32205 often performs well in environments where premature failure of austenitic grades is observed.
Duplex Heat Resistance
Duplex stainless steels are almost never used in environments above 300ºC. While the grade has good resistance to high temperature oxidation S32205, like other duplex stainless steels, suffers from embrittlement even for short periods in temperatures above 300ºC. This can only be rectified by a full solution annealing treatment.
Duplex Heat Treatment
Solution treatment (annealing) entails heating to 1020ºC-1100ºC and then rapid cooling. This grade cannot be hardened by thermal treatment, but does work harden.