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ASTM A182 F53 is a super duplex stainless steel forged bar. It matches UNS S32750, commonly called 2507, European standard EN 1.4410 (X2CrNiMoN25-7-4), and Chinese standard 022Cr25Ni7Mo4N. This material has a balanced two-phase structure of about 50% austenite and 50% ferrite. It gives both the good toughness of austenitic stainless steel and the high strength and stress corrosion resistance of ferritic stainless steel.
F53 is a super duplex stainless steel grade for forgings under ASTM A182/A182M. It is used to make forged bars, flanges, valves, pipe fittings, and other pressure-containing parts up to 4540 kg. Its PREN (pitting resistance equivalent number) is 40 or higher. It achieves a breakthrough balance of "high corrosion resistance + high strength and toughness" against chloride corrosion and overall mechanical properties.
Compared with regular duplex stainless steel F51 (2205), F53 pushes Cr, Mo, and N to higher levels. Its yield strength reaches 550 MPa, which is 3.2 times that of 316L. Under severe conditions with high chloride, high pressure, and structural loading all together, it provides pitting resistance close to that of 6Mo super austenitic steels, while its cost is only one-third of nickel alloy C276.
Standard | Grade |
ASTM | F53 |
UNS | S32750 |
Commercial | 2507 / SAF 2507 |
EN | 1.4410(X2CrNiMoN25-7-4) |
GB | 022Cr25Ni7Mo4N |
Element | wt% |
C | ≤0.030% |
Si | ≤0.80% |
Mn | ≤1.20% |
P | ≤0.035% |
S | ≤0.020% |
Cr | 24.0 – 26.0% |
Ni | 6.0 – 8.0% |
Mo | 3.0 – 5.0% |
N | 0.24 – 0.32% |
Cu | ≤0.50% |
Fe | bal. |
Property | value |
tensile strength | 800 – 950 MPa |
yield strength Rp0.2 | 650 – 750 MPa |
elongation | 25 – 35% |
reduction of area | ≥45% |
-50℃ Shahabi Impact | ≥27 J（典型80 – 120 J） |
-46℃ Low-temperature impact energy | ≥65 J |
density | 7.8 g/cm³ |
elasticity modulus | 200 GPa |
Maximum continuous operating temperature | ≤315℃ |
The yield strength of F53 is more than twice that of 316L stainless steel. Under the same pressure-bearing conditions, it can significantly reduce the wall thickness and lighten the structural weight.
Process parameters | Requirement |
Forging | Using a multi-pass and low-strain deformation forging method, the deformation amount for each pass is controlled within 15% - 20%. |
Initial forging temperature | The temperature is usually controlled within the range of 1140 - 1180℃, at which point the material has the best plasticity. |
Final forging temperature | The temperature must be ≥ 950℃. When the temperature approaches this limit, the forging should be immediately stopped and the workpiece should be reheated in the furnace. The "forging temperature" must not be exceeded. |
Solution temperature | 1020 – 1100℃ |
Heat preservation time | Thick piece 1–2h，thin plate 30–60min |
Cooling | Rapid water quenching (must quickly pass through the brittle zone of 600–900℃) |
Target organization | Austenite/ Ferrite ≈ 50% each, balanced duplex structure |
The only effective heat treatment method for F53 is solution annealing, and it cannot be hardened through quenching or aging.
Chloride ion medium (seawater, brine, concentrated salt water): The critical pitting temperature and crevice corrosion temperature are much higher than those of 2205 and 904L.
Acidic oil and gas (containing H₂S + CO₂ + chloride ions): Anti-sulfide stress corrosion (SSCC), meeting NACE MR0175 standards for acidic oil and gas.
FGD slurry for wet flue gas desulfurization: Resistance to erosion and pitting.
Seawater service: Can withstand up to approximately 50°C (F51 is applicable only to normal temperature seawater).
The yield strength is ≥ 550 MPa, which is more than twice that of 316L.
Under the same pressure conditions, the wall thickness can be reduced and the structural weight can be decreased.
Suitable for open die forging and machining
Good weldability
Available in various forms such as round steel, bars, forgings, flanges, pipe fittings, etc.
Industry | Application |
Petroleum and natural gas industry | Deep-sea oil and gas platform components, underwater wellhead equipment Ball valve pressure-bearing components and control pressure components High-pressure manifold, wellhead flange, production tree components Acidic natural gas treatment: inlet separator flange, slug flow catcher connection |
Marine engineering | Seawater desalination equipment (high-pressure pipe, seawater pipe) Submarine pipelines, mooring system Seawater pumps, seawater heat exchangers Propeller shaft, rudder |
Chemical Engineering and Energy | Chemical processing equipment (thermal chloride brine, ferric chloride, concentrated seawater system) Flue gas desulfurization system (FGD), scrubber system, absorption tower Pressure vessels, heat exchangers Pulp and paper industry (digesters, bleaching scrubbers) |
General industry | High-strength + highly corrosion-resistant mechanical structural components Fasteners, instruments and meters Chemical transport ships |
product condition | reference price （USD/kg） | remark |
round bar（black） | 5 – 8 USD | φ10–100mm |
Forgings / Flanges / Customized Parts | 10 –15 USD | High processing complexity. Pricing is based on both quantity and weight. |
polish bar | Increase by more than 20% | precision machined surface |
F53 Price influencing factors:
Specification and size (diameter, length)
Purchase batch (minimum order quantity)
Processing accuracy (black skin / polished rod / polished finish)
Quality certificate requirements (EN 10204 3.1/3.2)
Third-party inspection (class society certification, etc.)
The cost of F53 is approximately +30–50% higher than that of F51 (2205), but its lifespan and reliability advantages in high-corrosion conditions far outweigh the cost difference.
What is the relationship between F53 and 2507?
F53 is the designation of a grade in the ASTM A182 forging standard, while 2507 is the commercial common name for this material. Both correspond to the same UNS number S32750, which is different names for the same material under different standard systems.
What are the differences between F53 and F51 (2205)? When should one choose F53?
F51 is a conventional duplex stainless steel (PREN 34–36), while F53 is a super duplex stainless steel (PREN 41–43). When the working conditions meet the following criteria, F53 should be selected: Presence of chloride-containing media and temperature exceeding 40℃ Acidic oil and gas environment requiring PREN > 40 (NACE MR0175) Subsea valve bodies and wellhead equipment are exposed to high-temperature and high-salt produced water
What is the delivery status of the F53 forged bar?
The standard delivery condition of F53 forged bars is solution annealing followed by water quenching (1020–1100℃ for solution treatment, then rapid water cooling).
Which quality certificates are available for the F53 forged bar?
Certificates of EN 10204 3.1 or 3.2 can be provided, and additional certifications from third-party classification societies such as TÜV, DNV, ABS, Lloyd's Register, RINA, and BV can also be attached.
What are the supply specifications for the F53 forged bars?
We can supply various forms of products including round steel, bars (black skin/finished bars/finished surface), forgings, square steel, rings, flanges, pipe fittings, etc. The typical diameter range of round bars is from 16mm to 406.4mm. Larger sizes can be customized upon negotiation.
1 Produced strictly in accordance with the ASTM A182/A182M standard, with full control over chemical composition, mechanical properties, and microstructure.
2 100% solution treatment + water quenching, ensuring an equilibrium dual-phase structure of austenite/ferroite (40–60%)
3 Fully measurable: tensile strength, yield strength, elongation, hardness, -46℃ impact, ferrite content, PREN
4 Can provide EN 10204 3.1/3.2 certificates and third-party inspection certifications
5 Comprehensive specifications, supporting non-standard customization
