Project Description
Overview
F51 (W.Nr. 1.4462, UNS S31803 / S32205, commonly called 2205) is a nitrogen-alloyed DSS with approximately equal proportions of austenite and ferrite. The dual-phase structure delivers roughly twice the yield strength of standard 316L austenitic grades while offering superior resistance to stress corrosion cracking, pitting, and crevice corrosion in aggressive chloride and hydrogen sulphide environments. It is the most widely used duplex grade globally, accounting for approximately 80% of total duplex production, and is primarily applied in oil & gas, chemical processing, marine engineering, and pulp & paper industries.
Equivalent Grades
| Standard | Grade / Designation | Standard No. |
|---|---|---|
| ASTM | F51 (UNS S31803) / F60 (UNS S32205) | A182, A276, A479, A240, A789, A790, A928 |
| EN / DIN | 1.4462 / X2CrNiMoN22-5-3 | EN 10088-3, EN 10028-7, EN 10216-5, EN 10217-7, EN 10222-5, EN 10250-4 |
| JIS | SUS 329J3L | JIS G4304 |
| GB (China) | 022Cr22Ni5Mo3N | GB/T 20878 |
| ISO / NACE | X2CrNiMoN22-5-3 (S31803) | ISO 15156 / NACE MR0175, NORSOK MDS D41–D45, D47–D48 |
S32205 (F60) is a tighter compositional variant; it can be dual-certified as S31803 (F51), but not vice versa.
Applications
Oil & Gas
Subsea pipelines, pressure vessels, weld-neck flanges, gate valves, chokes, Xmas trees, manifolds, bolting connectors, compressor internals
Chemical Processing
Shell-and-tube heat exchangers, reactors, chemical storage tanks, scrubbers, distillation columns, phosphoric acid equipment
Marine & Desalination
Propeller shafts, rudder stocks, shaft seals, pump casings, impellers, seawater desalination evaporators, offshore structural members
Pulp & Paper
Bleaching vessels, digesters, washing drums, white-liquor piping, rotary press rolls
Supply Forms & Sizes
| Form | Typical Sizes | Applicable Standards |
|---|---|---|
| Round Bar | Ø 2–250 mm; L 3–13 m (hot-rolled, forged, ground) | ASTM A276, A182, A479; EN 10088-3, EN 10060, EN 10278 |
| Flat Bar / Block | Forged / sawn; discs, rings — on request | EN 10059, EN 10250-4, EN 10222-5 |
| Plate / Sheet | T 3–100 mm; W 1000–2500 mm; L up to 8000 mm | ASTM A240; EN 10028-7, EN 10088-2 |
| Seamless Pipe / Tube | OD×WT: 21.3×2.6 – 232.9×9.52 mm; L 5–7 m | ASTM A789 / A790 (ASME SA789/790); EN 10216-5 |
| Welded Tube | Various OD; on request | ASTM A928; EN 10217-7 |
| Wire | On request | ASTM A580 |
Chemical Composition
Per ASTM A182 / UNS S31803 & EN 10088-3 (1.4462 / X2CrNiMoN22-5-3) — wt.%, balance Fe
| C | Mn | Si | P | S | Cr | Ni | Mo | N |
|---|---|---|---|---|---|---|---|---|
| ≤0.030 | ≤2.00 | ≤1.00 | ≤0.035 | ≤0.015 | 21.0–23.0 | 4.5–6.5 | 2.5–3.5 | 0.10–0.22 |
PREN = %Cr + 3.3×%Mo + 16×%N ≈ 33–34 typical
Mechanical Properties
Condition: Solution annealed 1020–1100°C + rapid quench — per EN 10088-3 / ASTM A182, room temperature, bar ≤160 mm dia.
| UTS (MPa) | 0.2% Proof Strength (MPa) | Elongation A (%) | Hardness (HB max) | Impact KV (J) |
|---|---|---|---|---|
| 650–880 | ≥ 450 | ≥ 25 | 270 | 100 |
Not recommended above 300°C (risk of embrittlement). Cannot be hardened by heat treatment; work hardening only. Density: 7.8 kg/dm³.