Duplex Stainless Steel
Duplex 2205 Buttweld Pipe Fittings
Ferritic-austenitic stainless steel (UNS S32205 / S31803, EN 1.4462) — elbows, tees, reducers and caps to ASME B16.9 / ASTM A815, 1/2" to 24" NB. Double the strength of 316L with PREN ~35 chloride resistance. EN 10204 3.1 / 3.2 traceable.
Grade Overview
Duplex 2205 (UNS S32205 / S31803, EN 1.4462) is the workhorse duplex stainless steel, with a roughly 50/50 ferrite-austenite microstructure. That dual-phase structure gives it about twice the yield strength of standard 316L austenitic stainless, together with markedly better resistance to chloride pitting, crevice corrosion and — critically — chloride stress-corrosion cracking, the failure mode that limits 304/316 in warm chloride service.
Buttweld fittings in 2205 are covered by ASTM A815 (WP-S32205) to ASME B16.9 dimensions. After hot forming, fittings are solution annealed and water quenched to restore phase balance. Supplied with EN 10204 3.1 or 3.2 certification and PREN reporting on request.
Chemical Composition — S32205 / 1.4462
| Element | Requirement | Note |
|---|---|---|
| Chromium (Cr) | 22.0 – 23.0% | Pitting & oxidation resistance |
| Nickel (Ni) | 4.5 – 6.5% | Austenite stabiliser |
| Molybdenum (Mo) | 3.0 – 3.5% | Pitting resistance |
| Nitrogen (N) | 0.14 – 0.20% | Strength, austenite & pitting |
| Carbon (C) | ≤ 0.030% | Low-carbon, sensitization control |
| Manganese (Mn) | ≤ 2.00% | — |
PREN = %Cr + 3.3 × %Mo + 16 × %N ≈ 35, giving strong resistance to chloride pitting.
Mechanical Properties — Duplex 2205
| Property | Requirement |
|---|---|
| Tensile Strength (min) | 620 MPa (90 ksi) |
| Yield Strength (min) | 450 MPa (65 ksi) |
| Elongation (min) | ≥ 25% |
| Hardness (max) | ≤ 31 HRC / 290 HBW |
| Heat Treatment | Solution annealed ~1040°C + water quench |
Equivalent Grades
| Product Form | Specification |
|---|---|
| Buttweld fittings | ASTM A815 WP-S32205 / S31803 |
| EN designation | EN 1.4462 (X2CrNiMoN22-5-3) |
| Seamless pipe | ASTM A790 / A928 UNS S32205 |
| Forgings / flanges | ASTM A182 F51 / F60 |
Fitting Types Available in Duplex 2205
- Elbows — 45° / 90° / 180°, LR & SR (B16.9 / B16.28)
- Tees — equal & reducing (B16.9)
- Reducers — concentric & eccentric
- Caps — buttweld end closures
- Stub Ends — Type A & B for lap joints
- Laterals & Crosses — branch connections