Alloy 2205
Also known as UNS S32205 / S31803, EN 1.4462
Alloy 2205 is a 22% chromium duplex stainless steel, stronger and more corrosion-resistant than austenitic grades like 316L.
Alloy 2205 (UNS S32205 / S31803) is a 22% chromium duplex stainless steel with a Pitting Resistance Equivalent Number (PREN) of 34, combining approximately twice the yield strength of standard austenitic grades with superior resistance to pitting, crevice corrosion and stress corrosion cracking in chloride and H₂S environments.
Listed in NACE MR0175 / ISO 15156 for sour service and approved under NORSOK MDS D45 and API 6A. Lower thermal expansion and higher thermal conductivity than austenitic grades make it particularly well suited to heat exchanger applications.
We stock bar in the UK and USA, and plate in the USA. Tube and fittings are available on enquiry; forgings and castings to order.
- Higher strength than standard stainless steels
- Higher corrosion resistance than Alloy 316L in sulphuric, phosphoric and nitric acids
- Good resistance to pitting and crevice corrosion in seawater
- High stress corrosion resistance
- Lower thermal expansion than austenitic stainless steels
- Higher thermal conductivity than austenitic stainless steels
| Element | Min | Max |
|---|---|---|
| Chromium (Cr) | 22.00 | 23.00 |
| Nickel (Ni) | 4.50 | 6.50 |
| Molybdenum (Mo) | 3.00 | 3.50 |
| Nitrogen (N) | 0.14 | 0.20 |
| Manganese (Mn) | - | |
| Silicon (Si) | 0.20 | 0.70 |
| Carbon (C) | - | 0.03 |
| Phosphorus (P) | - | 0.030 |
| Sulphur (S) | - | 0.020 |
| Iron (Fe) | Bal | |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 65.3 ksi | 450 N/mm² |
| Tensile strength (min) | 95.0 ksi | 655 N/mm² |
| Elongation (5.65√S0) | 25% | |
| Reduction of area | 45% | |
| Hardness (Brinell) | ≤ 270 HB | |
| Impact strength (-46°C) | 80 J |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 65.3 ksi | 450 N/mm² |
| Tensile strength (min) | 95.0 ksi | 655 N/mm² |
| Elongation (5.65√S0) | 25% | |
| Reduction of area | 45% | |
| Hardness (Brinell) | ≤ 270 HB | |
| Impact strength (-46°C) | 45 J (35 J min) |
| Property | Imperial | Metric |
|---|---|---|
| 0.2% Proof stress (min) | 65.3 ksi | 450 N/mm² |
| Tensile strength (min) | 95.0 ksi | 655 N/mm² |
| Elongation (5.65√S0) | 25% | |
| Reduction of area | 45% | |
| Hardness (Brinell) | ≤ 270 HB | |
| Impact strength (-46°C) | 80 J |
| Property | Value |
|---|---|
| Density (kg/m³) | 7810 |
| Magnetic permeability (20°C) | < 50 |
| Young's modulus (kN/mm²) | 190 |
| Specific electrical resistance, 20°C (µΩ.m) | 0.85 |
| Mean coefficient of thermal expansion, 20-300°C (m/m/°C) | 11 x 10⁻⁶ |
| Specific heat, 20°C (J/kg.K) | 400 |
| Thermal conductivity, 20°C (W/m.K) | 15 |
Equivalents & cross-references
Standard designations
- UNS
- S32205Current primary designation; ASTM F60 S31803Earlier designation; ASTM F51 - both cover 22% Cr duplex
- EN
- 1.4462European harmonised standard; X2CrNiMoN 22.5.3
- ASTM
- A182 F51Forgings - S31803 A182 F60Forgings - S32205 A479Bar and shapes
- NORSOK
- MDS D47Material data sheet
- NACE
- MR0175 / ISO 15156Sour service
- API
- 6AWellhead and tree equipment
Alloy 2205 is also designated UNS S32205, UNS S31803, EN 1.4462, ASTM A182 F51, ASTM A182 F60, ASTM A479, NORSOK MDS D47, NACE MR0175 / ISO 15156 and API 6A.
Common questions
What is Alloy 2205?
Alloy 2205 is a 22% chromium duplex stainless steel supplied in the solution annealed condition, covered by UNS S32205 (F60) and UNS S31803 (F51), with equivalents ASTM A479, ASTM A182 F51/F60 and EN 1.4462 (X2CrNiMoN 22.5.3). It has a Pitting Resistance Equivalent Number (PREN) of 34 and is listed in NACE MR0175/ISO 15156, NORSOK MDS D45 and API 6A. Langley Alloys stocks it as bar and plate; tube and fittings are available on enquiry, and forgings and castings are to order.
What is Alloy 2205 used for?
Alloy 2205 is used for oil and gas pumps, valves, pipe, vessels, wellhead and subsea equipment, separators and heat exchangers; marine propellers, shafts, shaft seals, pumps, fasteners and valves; and oil and chemical tankers. It is also used in process components for sulphuric, nitric and phosphoric acid, polypropylene and PVC production, pollution control and flue gas desulphurisation, pulp and paper equipment, and food industry equipment such as brewery piping and evaporators.
How does Alloy 2205 compare with Alloy 316L?
Alloy 2205 offers higher corrosion resistance than Alloy 316L austenitic stainless steel in a wide variety of corrosive chemicals, with a PREN of 34 against 316L's lower rating, and good resistance to pitting and crevice corrosion in seawater. Its yield strength is about twice that of austenitic stainless steels (0.2% proof stress of 450 N/mm²), allowing designers to save weight and make the alloy more cost competitive than Alloy 316L or 317L. It also has lower thermal expansion and higher thermal conductivity than austenitic steels.
Is Alloy 2205 suitable for sour wells?
Yes. Alloy 2205's excellent corrosion properties make it well-suited to environments containing chlorides and hydrogen sulphide, for use in oil and gas extraction from sour wells, in refineries and in process solutions contaminated with chlorides. It is listed in NACE MR0175/ISO 15156 and has high stress corrosion resistance.
What is the difference between UNS S31803 and S32205?
UNS S31803 and S32205 both designate 22% chromium duplex stainless steel (EN 1.4462), differing slightly in their minimum nitrogen and molybdenum requirements. S32205 is the tighter, more widely specified designation; many specifications now reference S32205 (F60) in place of the older S31803 (F51). Langley Alloys stocks both under the single grade designation Alloy 2205.
What is EN 1.4462 stainless steel?
EN 1.4462 (X2CrNiMoN 22.5.3) is the European designation for duplex stainless steel UNS S32205/S31803, stocked by Langley Alloys as Alloy 2205. It meets ASTM A479, A182 F51/F60, NACE MR0175/ISO 15156, NORSOK MDS D45, and API 6A.
What is ASTM A182 F51?
ASTM A182 F51 is the forging designation for UNS S31803, the earlier designation for 22% Cr duplex stainless steel (EN 1.4462). The current tighter designation is F60 for S32205. Langley Alloys stocks this grade as Alloy 2205.
What is ASTM A182 F60?
ASTM A182 F60 is the forging designation for UNS S32205, the current preferred designation for 22% Cr duplex stainless steel (EN 1.4462). Langley Alloys stocks this grade as Alloy 2205 to ASTM A479, A182 F51/F60, NORSOK MDS D45, and NACE MR0175/ISO 15156.
What is the density of Alloy 2205?
Alloy 2205 has a density of approximately 7.81 g/cm³ (7810 kg/m³).
Is Alloy 2205 magnetic?
Yes. Alloy 2205 is a duplex stainless steel with a part-ferritic structure, so it is ferromagnetic (magnetic).
Bars are supplied peeled and polished to a surface finish of 125CLA or better, solution treated at 1060-1120°C and water quenched, with each bar ultrasonically tested and visually inspected.
Processing capability
Cutting
Automated band sawing to 650mm section. CNC sawing at all sites.
Cutting servicesFirst-stage processing
Water jet cutting, turning, boring and grinding undertaken in-house.
Processing servicesInspection & testing
Each bar ultrasonically tested and visually inspected. Ferrite content certification available.
Inspection & testing
Tools for this grade
Pitting & crevice resistance
Pitting & Crevice Resistance
Rank alloys by PREN and get an indicative pitting temperature for a chloride service. Pick a grade and a service temperature to see whether it has margin against pitting, or compare the range in the table below. A first-pass screen for chloride and seawater service.
| Grade | UNS | PREN | Indicative CPT | Relative pitting resistance |
|---|
Indicative screen, not a certified result. PREN ranks pitting resistance; the pitting temperature here is estimated from PREN (CPT ≈ 2.5 × PREN - 50), consistent with Langley's "PREN >40, CPT exceeding 50°C" for super duplex. Real critical pitting/crevice temperature depends on test method, product form, surface finish and service chemistry. Crevice corrosion starts well below the pitting temperature - allow a margin at gaskets, deposits and flange faces. Use certified data for design.
Sour-service screen (NACE MR0175)
Sour-Service Screen
Work out whether a service is sour from the H2S partial pressure, and see each alloy's NACE MR0175 / ISO 15156 status and hardness limit. A first-pass screen for oil & gas material selection - the full environmental envelope for a grade is set in ISO 15156-3 Annex A.
Candidate grade
| Grade | Family | NACE status | Hardness limit |
|---|
First-pass screen only. This shows whether the service is sour (from H2S partial pressure) and each material group's NACE MR0175 hardness limit and general suitability. It does not reproduce the full environmental windows (maximum H2S partial pressure, temperature, chloride, in-situ pH per grade) - those are in ISO 15156-3 Annex A and must be checked there for the specific grade, product form and condition. Qualification also depends on heat treatment, cold work and welding.
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