2205 steel (S32205): properties, composition, equivalents
2205 duplex stainless steel (UNS S32205 / S31803, F51/F60): 22 % Cr, 5 % Ni, 3 % Mo, 0.16 % N. 450 MPa (65 ksi) yield, 655 MPa (95 ksi) tensile, PREN ≥ 35, magnetic. Composition, S31803 vs S32205, properties, 1.4462/SUS329J3L equivalents.
What is 2205?
2205 is the standard duplex stainless steel — the alloy most often specified when 316L is not strong or corrosion-resistant enough but super-duplex or nickel alloys are unnecessary. Its microstructure is roughly 50 % ferrite and 50 % austenite, which gives it about twice the yield strength of 316L (450 vs 205 MPa), a pitting resistance equivalent of 35 or more (316L: 24), excellent resistance to chloride stress-corrosion cracking, and good weldability in modern nitrogen-balanced heats. Two UNS numbers apply: S31803 (the original 1980s window) and S32205 (from 2000, guaranteeing Cr ≥ 22, Mo ≥ 3, N ≥ 0.14 and therefore PREN ≥ 35). Nearly all current production meets both and is dual-certified; specify S32205 for new work. ASTM A182 forgings are F51 (S31803) and F60 (S32205).
The high strength lets designers cut vessel and pipe wall thickness by 30–50 % versus austenitic steel, which is why 2205 dominates in chemical tankers, storage tanks, pressure vessels, heat exchangers, desalination plant, pulp-and-paper digesters, offshore piping and, increasingly, structural applications such as bridges and rebar in marine environments.
Limits: a service window of about −50 to +300 °C (sigma-phase and 475 °C embrittlement outside it), ferromagnetism, and higher forming loads. EN 1.4462, JIS SUS329J3L and GB 022Cr23Ni5Mo3N are the same grade.
2205 chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | ≤ 0.03 | |
| Mn | ≤ 2 | |
| P | ≤ 0.03 | |
| S | ≤ 0.02 | |
| Si | ≤ 1 | |
| Cr | 22 – 23 | S31803: 21.0–23.0 |
| Ni | 4.5 – 6.5 | |
| Mo | 3 – 3.5 | S31803: 2.5–3.5 |
| N | 0.14 – 0.2 | S31803: 0.08–0.20 |
ASTM A240/A240M-22 Table 1 (S32205). S31803 is the original, wider 2205 window; S32205 (introduced 2000) guarantees the higher-Cr/Mo/N end and PREN ≥ 35. Most modern plate is dual-certified S31803/S32205. EN 1.4462 (X2CrNiMoN22-5-3): Cr 21–23, Ni 4.5–6.5, Mo 2.5–3.5, N 0.10–0.22.
2205 mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| S32205 plate, sheet, strip — annealed (A240) | ≥ 450 (≥ 65.3) | ≥ 655 (≥ 95.0) | 25 | ≤ 293 HB / ≤ 31 HRC |
| S31803 plate, sheet, strip — annealed (A240) | ≥ 450 (≥ 65.3) | ≥ 620 (≥ 89.9) | 25 | ≤ 293 HB / ≤ 31 HRC |
| Bar — annealed (A276 / A479) | ≥ 450 (≥ 65.3) | ≥ 620 (≥ 89.9) | 25 | ≤ 290 HB |
| Seamless/welded pipe (A790 / A789) | ≥ 450 (≥ 65.3) | ≥ 620 (≥ 89.9) | 25 | ≤ 290 HB / ≤ 30 HRC |
| Forgings F51 / F60 (A182) | ≥ 450 (≥ 65.3) | ≥ 620 / ≥ 655 (≥ 89.9 / ≥ 95.0) | 25 | ≤ 290 HB |
| EN 1.4462 hot-rolled plate +AT (for comparison) | ≥ 460 (≥ 66.7) | 640–840 (92.8–121.8) | 25 | ≤ 270 HB |
Minimums per ASTM A240/A276/A790/A182. Typical plate: yield 500–560 MPa, tensile 720–780 MPa, elongation 30–35 %. Charpy typical ≥ 100 J at +20 °C, ≥ 40 J at −40 °C; ASME requires impact testing below −29 °C for some product forms.
Impact toughness
2205 requires a minimum Charpy V-notch energy of 40 J at -40 °C (typical; ASTM A923 test method C for intermetallic detection). Duplex steels show a ductile-to-brittle transition; practical minimum service temperature −50 °C (ASME −40 °F for most forms).
2205 equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| 318S13 | BS (superseded British) | Identical | BS 1449 318S13 (withdrawn). |
| 1.4462 | EN (European) | Identical | X2CrNiMoN22-5-3: EN window covers both S31803 and S32205; modern 1.4462 plate is dual-certified S32205. |
| 022Cr23Ni5Mo3N | GB/T (China) | Identical | GB/T 20878 022Cr23Ni5Mo3N (formerly 00Cr22Ni5Mo3N). |
| SUS329J3L | JIS (Japan) | Identical | JIS G4304 SUS329J3L: Cr 21–24, Ni 4.5–6.5, Mo 2.5–3.5, N 0.08–0.20 (S31803 window). |
| 03Kh22N5AM3 | GOST (Russia/CIS) | Near | Russian TU/GOST R designations for 2205-type duplex; not in the classic GOST 5632 list. |
| 2304 (S32304 / 1.4362) | AISI / SAE | Functional | Lean duplex: 23 Cr, 4 Ni, no Mo, PREN ≈ 25 — cheaper, for less aggressive service. |
| 2507 (S32750 / 1.4410) | AISI / SAE | Functional | Super-duplex: 25 Cr, 7 Ni, 4 Mo, PREN ≥ 40 — for hot seawater and sour service. |
| 316L | AISI / SAE | Functional | Austenitic 316L: half the yield, PREN 24 — the grade 2205 usually replaces to save wall thickness. |
| 316 | AISI / SAE | Functional | Duplex S32205: double the yield, PREN 35 — the upgrade for warm chloride service. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for 2205 →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| S31803 | UNS (1980s) | Original 2205 designation; wider Cr/Mo/N window. Still valid; most material meets both. |
| F51 / F60 | ASTM A182 | Forging grades: F51 = S31803, F60 = S32205. |
| 1.4462 / X2CrNiMoN22-5-3 | EN 10088 | European designation. |
| SAF 2205 | Sandvik trade name | Origin of the generic name; Uranus 45N, Avesta 2205, Outokumpu 2205 are equivalents. |
| CD3MN / 4A | ACI / ASTM A890, A995 | Cast equivalents. |
Product forms and tolerance standards
Product forms: plate, sheet and strip (ASTM A240), bar and forgings (A276, A479, A182 F51/F60), seamless and welded pipe and tube (A790, A789, A928), fittings (A815 WP-S), flanges, castings CD3MN / 4A (A890, A995), wire and fasteners.
Dimensional tolerances: plate/sheet: ASTM A480; bar: ASTM A484; pipe: ASTM A999 / ASME B36.19.
Key property values
2205 yield strength
Minimum 450 MPa (65 ksi) in all wrought product forms (ASTM A240, A276, A790); typical 500–560 MPa. Design codes: ASME uses 65 ksi; EN 1993-1-4 uses 460 MPa.
2205 tensile strength
S32205: ≥ 655 MPa (95 ksi); S31803: ≥ 620 MPa (90 ksi); typical 720–780 MPa.
2205 hardness
Annealed max 293 HB / 31 HRC (plate), 290 HB (bar, pipe); typical 250–270 HB. NACE MR0175: ≤ 28 HRC for solution-annealed wrought 2205 in sour service (36 HRC for cold-worked tubing under specific limits). Not hardenable by heat treatment.
Corrosion resistance
PREN = Cr + 3.3 Mo + 16 N: ≥ 35 for S32205 (typ. 35–37), 31–35 for low-end S31803. Critical pitting temperature (ASTM G48 A) ≈ 40–50 °C; critical crevice temperature ≈ 20–25 °C. Resists chloride SCC in boiling 25 % NaCl (316L fails), organic acids, dilute sulphuric acid, alkalis, and seawater at ambient temperature with flow. Not for hot stagnant seawater or strong reducing acids.
Service temperature
−50 °C to +300 °C (ASME −40 °F to 600 °F / 315 °C; EN 13445 to 250–280 °C). Above 300 °C: 475 °C embrittlement; 700–950 °C: sigma/chi phases form within minutes at 850 °C. Never use as a high-temperature alloy.
Physical properties
Density 7.8 g/cm³, E = 200 GPa, expansion 13.7 × 10⁻⁶/K (20–100 °C — between carbon and austenitic steel), conductivity 19 W/m·K, resistivity 0.80 µΩ·m, ferromagnetic.
Heat treatment
Solution anneal 1020–1100 °C (1870–2010 °F), rapid water quench — the only permitted heat treatment. No stress relief (350–950 °C is forbidden). Hot forming 1230–950 °C followed by full re-anneal and quench; verify absence of intermetallics per ASTM A923.
Weldability
Weldable by GTAW, GMAW, SMAW, SAW, FCAW and plasma with over-alloyed ER2209 / E2209 filler (≈ 9 % Ni) so the weld metal solidifies to a balanced ferrite/austenite ratio. Heat input 0.5–2.5 kJ/mm, interpass ≤ 150 °C (≤ 100 °C for thick sections), no preheat, no PWHT. Argon + 2–5 % N₂ shielding/backing preserves nitrogen; autogenous welds are not permitted for pressure parts. Qualify procedures with ferrite measurement (30–70 %) and ASTM A923 or G48 corrosion tests. Dissimilar joints to carbon steel or 316L: ER2209 or ER309LMo.
Machining, forming and heat treatment
Machinability ≈ 30 % of B1112 — high strength and work hardening: rigid setups, sharp carbide (positive rake), low speed / high feed, flood coolant. Cold forming needs ~50 % more force than 316L and generous bend radii (≥ 2 t); spring-back is large. Deep drawing is limited. Hot forming 1230–950 °C then anneal. Abrasive cutting, plasma and laser cutting are routine; keep cut edges cool.
Typical applications
- Chemical tankers cargo tanks, road and rail tankers
- Pressure vessels, columns, storage tanks (ASME VIII, EN 13445) — thinner walls than 316L
- Heat exchangers, condensers, evaporators with brackish or chloride-bearing cooling water
- Desalination: SWRO high-pressure piping, MSF evaporator shells
- Offshore: process piping, firewater systems, risers, umbilical tubes, subsea manifolds
- Pulp and paper: digesters, bleach plant, white-liquor and black-liquor equipment
- Oil and gas: flowlines, OCTG (cold-worked), sour-service equipment within NACE limits
- Structural: bridges, walkways, rebar, marine architecture; biogas and FGD plant
Frequently asked questions
What is the difference between S31803 and S32205?
Both are called 2205. S31803 (1980s) allows Cr 21–23, Mo 2.5–3.5, N 0.08–0.20; S32205 (2000) narrows this to Cr 22–23, Mo 3.0–3.5, N 0.14–0.20 to guarantee PREN ≥ 35 and better weldability. Nearly all modern material meets both and is dual-certified — specify S32205 for new designs.
Is 2205 duplex magnetic?
Yes. The 50 % ferrite phase makes it ferromagnetic — a quick field check distinguishing it from 316L.
What is the maximum temperature for 2205?
About 300 °C (ASME 315 °C / 600 °F; European codes 250–280 °C). Above that, 475 °C embrittlement and, at 700–950 °C, sigma phase destroy toughness and corrosion resistance. Minimum is about −50 °C.
How much stronger is 2205 than 316?
Minimum yield 450 MPa vs 205 MPa — more than double — and tensile 655 vs 515 MPa. Vessel walls can typically be 30–50 % thinner, which often offsets the higher price per tonne.
Can 2205 be welded without filler?
Not for pressure or corrosion-critical parts: autogenous welds solidify almost fully ferritic and are brittle with poor corrosion resistance. Use ER2209 filler and nitrogen-bearing shielding gas; if autogenous welding is unavoidable (thin tube), a full solution anneal afterwards is required.
What is 2205 equivalent to in EN?
EN 1.4462 (X2CrNiMoN22-5-3). Modern 1.4462 plate is melted to the S32205 window and dual-certified; ASTM forgings F51 (S31803) and F60 (S32205) both map to 1.4462.
Related grades
Verified against ASTM A240/A240M-22; ASTM A240/A240M-22 Tables 1–2; ASTM A790/A790M-22; ASTM A182/A182M-23 (F51/F60); ASTM A923-22; NACE MR0175/ISO 15156-3. Last checked: September 2026.