ASTM A182 F51 Forgings (UNS S31803 / Duplex 2205)
Jiangyin Jiangnan Metal Co., Ltd. forges ASTM A182 Grade F51 to customer drawings at our open-die shop in Jiangyin, Jiangsu. Forms include seamless rolled rings, flanges, shafts, round bars, discs, sleeves, bushings, tube sheets and valve parts, supplied solution annealed with EN 10204 3.1 or 3.2 certification.
Technical data checked against ASTM A182 requirements. Updated .
A182 F51 data summary
- Grade designation ASTM A182 / ASME SA-182 Grade F51
- UNS number S31803
- Trade name Duplex 2205
- Equivalents EN 1.4462, SAF 2205
- Structure Ferritic-austenitic (duplex), ferrite 40-60%
- Tensile strength 620 MPa (90 ksi) min
- Yield strength 450 MPa (65 ksi) min
- Elongation 25% min
- Hardness 293 HBW (31 HRC) max
- PREN 34-36 typical
- Heat treatment Solution anneal 1020-1100 °C, water quench
- Max service temperature 315 °C (600 °F)
- Cast equivalent ASTM A995 Grade 4A
What ASTM A182 F51 is
ASTM A182 Grade F51 is the forging designation for duplex stainless steel UNS S31803, sold in the trade as duplex 2205. It carries 21-23% chromium, 4.5-6.5% nickel, 2.5-3.5% molybdenum and a controlled nitrogen addition, and it solidifies into a structure of roughly half ferrite and half austenite. That mix gives F51 about twice the minimum yield strength of austenitic F316, together with far better resistance to chloride stress corrosion cracking, pitting and crevice corrosion. The nitrogen is there to lift corrosion performance and keep the grade weldable.
F51 (S31803) against F60 (S32205)
S32205, grade F60, is the tighter and more highly alloyed version of 2205, with a higher nitrogen range. Material can be dual certified as S32205 and S31803, but the reverse does not hold. If your specification calls for S32205, plain S31803 will not pass, so confirm the UNS number on the purchase order before we release a heat.
Chemical composition
| Element | Requirement | Element | Requirement |
|---|---|---|---|
| Carbon (C) | 0.030 max | Chromium (Cr) | 21.00 - 23.00 |
| Manganese (Mn) | 2.00 max | Nickel (Ni) | 4.50 - 6.50 |
| Silicon (Si) | 1.00 max | Molybdenum (Mo) | 2.50 - 3.50 |
| Phosphorus (P) | 0.030 max | Nitrogen (N) | 0.08 - 0.20 |
| Sulfur (S) | 0.020 max | Iron (Fe) | Balance |
Forging stock is melted by EAF plus AOD or VOD. ESR remelt is available where tighter cleanliness is called for.
Mechanical properties
| Property | Metric | Imperial |
|---|---|---|
| Tensile strength, min | 620 MPa | 90 ksi |
| Yield strength, 0.2% offset, min | 450 MPa | 65 ksi |
| Elongation, min | 25% | 25% |
| Hardness, max | 293 HBW | 31 HRC |
| Ferrite content | 40 - 60% | 40 - 60% |
Heat treatment and forging practice
Parts are hot forged as close to finished shape as the geometry allows, cooled below 538 °C (1000 °F), then solution annealed at 1020-1100 °C and water quenched. The quench has to be fast enough to stop sigma phase and other intermetallics forming, which is why section thickness and quench tank capacity matter on heavy F51 rings and shafts.
Machining notes
F51 work hardens quickly and is harder on tooling than 316 or 316L. Coated carbide, rigid setups, reduced surface speed and plenty of coolant all help. Cut feed rates only slightly, because dropping feed too far glazes the cut surface and shortens tool life. We can supply parts rough machined with an agreed allowance, or finish machined to drawing.
Product forms in A182 F51
Seamless rolled rings
Ring rolled blanks for bearing races, flange rings, retaining rings and spacers.
Forged flanges
WN, SO, blind, LWN, spectacle blind, spade, spacer and orifice flanges to ASME B16.5, B16.47, EN 1092-1 and API 6A.
Shafts and spindles
Pump and compressor shafts, eccentric shafts, stems and crankshafts.
Discs and hubs
Forged blanks for gears, wheels, closures and tube sheets.
Round bars and blocks
Forged bar, square and rectangular blocks for valve bodies and manifolds.
Sleeves, bushings, tubes
Hollow forgings, forged pipe, nozzles and cylindrical liners.
Valve components
Bodies, bonnets, seat rings, stems and blocks for ball, gate, globe, check and plug valves.
Custom open-die work
Non-standard shapes forged to your drawing or 3D model.
Where A182 F51 is used
F51 gets specified where chlorides, moderate H2S or aggressive process chemistry rule out 304 and 316, and where the higher yield strength lets a designer use thinner sections.
- Offshore oil and gas: topside piping flanges, manifolds, subsea wellhead and Christmas tree parts, downhole components for moderately sour wells.
- Seawater and desalination: firewater and cooling water flanges, injection systems, high pressure reverse osmosis connections, separator and heat exchanger parts.
- Chemical and petrochemical: brine and chloride bearing acid service flanges, crystallizer equipment, reactor nozzles.
- Pulp and paper: digesters, liquor tanks, paper machine rolls and shafts.
- Power and rotating equipment: turbine and gas compressor parts, gearbox components, industrial air compressors, nitrogen generators.
- Marine and heavy machinery: shipbuilding parts, forged rolls and wheels.
Testing, inspection and certification
Every heat is tension tested, and one set of three Charpy V-notch specimens is tested per heat. Low temperature impact testing, for example at minus 46 °C, is available as a supplementary requirement.
| Test | Standard or method |
|---|---|
| Chemical analysis | Heat analysis, product analysis on request |
| Tension test | One per heat, per ASTM A182 |
| Impact test | Charpy V-notch, one set of three per heat |
| Intermetallic phase | ASTM A923, ASTM A1084 |
| Corrosion test | ASTM A923 Method C, ferric chloride pitting |
| Ferrite content | Metallographic or magnetic, 40-60% check |
| Ultrasonic testing | ASTM A388, EN 10228-3, SEP 1921 |
| Surface NDT | Liquid penetrant, magnetic particle where applicable |
| Certification | EN 10204 3.1 mill certificate, or 3.2 with third party witness |
ASTM A182 does not allow weld repair of F51 forgings, and machined surfaces are finished to the roughness limits of the specification.
Questions we get asked
Is ASTM A182 F51 the same as UNS S31803 and duplex 2205?
Yes. F51 is the ASTM A182 forging designation for UNS S31803, the alloy commonly called duplex 2205. The European equivalent is EN 1.4462, and it is also sold as SAF 2205. We supply forgings under any of these designations from the same qualified heats.
What is the difference between A182 F51 and A182 F60?
F51 is UNS S31803 and F60 is UNS S32205. S32205 is the tighter, higher nitrogen version of 2205. Material can be dual certified as S32205 and S31803, but S31803 only material cannot be substituted where S32205 is specified.
What are the minimum mechanical properties of A182 F51?
620 MPa (90 ksi) tensile strength minimum, 450 MPa (65 ksi) yield strength minimum, 25% elongation minimum, and hardness no higher than 293 HBW (31 HRC), in the solution annealed and water quenched condition.
What is the maximum service temperature of A182 F51?
Around 315 °C (600 °F). Above that the duplex structure is prone to embrittlement, so F51 is not suited to sustained elevated temperature service.
Can A182 F51 be used in sour service to NACE MR0175?
F51 is used in moderately sour service when the hardness limit of the applicable NACE MR0175 and ISO 15156 material data sheet is met, commonly below 28 HRC, along with the stated environmental limits. Send us your H2S partial pressure, chloride level and temperature and we will confirm before quoting.
Why choose F51 over 316 stainless?
F51 has roughly double the minimum yield strength of austenitic F316, 450 MPa against 205 MPa, a PREN near 35 against about 26, and much better chloride stress corrosion cracking resistance. The extra strength often allows thinner sections, which offsets part of the higher price per kilogram.
What paperwork comes with the forgings?
EN 10204 3.1 mill test certificates as standard, or EN 10204 3.2 with third party inspection, covering chemistry, mechanical properties, heat treatment records, ferrite content, corrosion results and NDT reports.