Duplex 2205: properties, composition, uses and standards
Duplex 2205 is a duplex (austenitic-ferritic) stainless steel, chosen for strength with chloride resistance at a stainless-steel budget. UNS S32205, W.Nr 1.4462, PREN ≈ 35, density 7.8 g/cm³.
What is Duplex 2205?
Duplex 2205 is a duplex (austenitic-ferritic) stainless steel. Engineers choose it for strength with chloride resistance at a stainless-steel budget. It is also known as UNS S32205 / S31803, W.Nr 1.4462, F51 / F60, SAF 2205.
- UNS
- S32205 · S31803
- W.Nr
- 1.4462
- EN
- X2CrNiMoN22-5-3
- Forging grade
- F51 (S31803) · F60 (S32205)
- Trade names
- SAF 2205 · 2205 Code Plus Two
- Density
- 7.8 g/cm³
- Melting range
- 1385 – 1445 °C
- Magnetic
- Magnetic (ferritic phase)
- PREN (approx.)
- ≈ 35
Chemical composition and what each element does
| Element | Weight % |
|---|---|
| Chromium | 22.0 – 23.0 |
| Nickel | 4.5 – 6.5 |
| Molybdenum | 3.0 – 3.5 |
| Nitrogen | 0.14 – 0.20 |
| Carbon | 0.030 max |
| Manganese | 2.00 max |
| Silicon | 1.00 max |
| Phosphorus | 0.030 max |
| Sulphur | 0.020 max |
| Iron | Balance |
Per ASTM A240 for UNS S32205.
A roughly 50/50 austenite-ferrite structure gives about twice the yield strength of 316L, so walls can be thinner.
Chromium, molybdenum and nitrogen give a PREN around 35 — well above 316L.
The ferrite phase gives far better resistance to chloride stress-corrosion cracking than austenitic grades.
Keep service below about 300 °C to avoid embrittlement.
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength | 655 MPa · 95 ksi |
| Yield strength 0.2% | 450 MPa · 65 ksi |
| Elongation | 25% |
| Hardness | 293 HB max |
Solution-annealed plate & sheet, minimum values. Values for pipe, bar and forgings differ slightly — see the product standard.
Where Duplex 2205 is used
- Oil & gas. Flowlines, manifolds and topside piping. Industry →
- Desalination. Evaporators and seawater piping. Industry →
- Chemical tankers. Cargo tanks and piping. Industry →
- Pulp & paper. Digesters and bleach plants. Industry →
- Structures. Bridges and offshore structures where weight matters. Industry →
Welding 2205
The matching filler is ER2209 (AWS A5.9). Control heat input 0.5–2.5 kJ/mm to keep the phase balance.
Keep heat input moderate and interpass temperature low, clean joints thoroughly, and pickle or passivate after welding where the service is corrosive.
Duplex 2205 compared with similar grades
| Grade | PREN | Choose it for |
|---|---|---|
| Duplex 2205 | ≈ 35 | Strength with chloride resistance at a stainless-steel budget |
| SS 316 / 316L | ≈ 24 | Chloride-bearing process fluids, marine air and pharmaceutical service |
| SS 904L | ≈ 35 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| Super Duplex 2507 | ≈ 42 | Seawater and high-chloride service where strength also matters |
Duplex 2205 standards by product
Buying Duplex 2205: what to specify
- The product standard and the UNS or designation — for example ASTM A240 UNS S32205.
- Size, thickness or schedule, and quantity in pieces and kg or metres.
- Heat-treatment condition where the standard offers a choice.
- Certificate: EN 10204 3.1 as standard, 3.2 if a third party must witness.
- NACE MR0175 / ISO 15156 compliance if the service contains H₂S.