UNS S32750 Forgings: Super Duplex Rings, Flanges, Bars and Discs
ASTM A182 F53 · EN 1.4410 (X2CrNiMoN25-7-4) · Super Duplex 2507 · PREN 41-43
UNS S32750 is a 25% chromium super duplex stainless steel with a roughly 50:50 ferrite and austenite microstructure. In forged form it is designated ASTM A182 F53; the European equivalent is EN 1.4410 (X2CrNiMoN25-7-4), and the common trade name is Super Duplex 2507. A PREN of 40 and above gives it high resistance to pitting, crevice corrosion and chloride stress corrosion cracking in warm seawater, at roughly twice the yield strength of 316L. Jiangyin Jiangnan Metal Co., Ltd. forges UNS S32750 to ASTM A182, supplied solution annealed and quenched with EN 10204 3.1 or 3.2 certification.
Equivalent Designations and Governing Standards
UNS S32750 is sold under several designations, and the most common sourcing error on super duplex enquiries is quoting the bar standard when the part is actually a forging. EN 1.4410 and ASTM A182 F53 cover the same alloy but set different minimum mechanical properties, so the purchase order should name the product form as well as the grade.
| System | Designation | Scope |
|---|---|---|
| UNS | S32750 | Unified alloy number |
| ASTM / ASME | A182 F53, SA-182 F53 | Forged flanges, fittings, valves, pressure parts |
| EN 10088-3 | 1.4410, X2CrNiMoN25-7-4 | Bar, semi-finished products, sections |
| Trade name | Super Duplex 2507, SAF 2507 | Commercial designation |
| NORSOK | MDS D51 to D55, D57, D58 | Offshore material data sheets |
| Sour service | NACE MR0175 / ISO 15156 | H2S containing environments |
| Cast equivalent | ASTM A995 Grade 5A | Cast valve and pump bodies |
| Other forms | A790 S32750 pipe, A815 S32750 fittings | Seamless pipe and buttweld fittings |
Chemical Composition
Nitrogen, molybdenum and manganese limits differ slightly between the forging standard and EN 10088-3, so both columns are given rather than averaged into a single figure.
| Element | ASTM A182 F53 (forgings) | EN 10088-3, 1.4410 |
|---|---|---|
| Carbon | 0.030 max | 0.03 max |
| Chromium | 24.0 - 26.0 | 24.0 - 26.0 |
| Nickel | 6.0 - 8.0 | 6.0 - 8.0 |
| Molybdenum | 3.0 - 5.0 | 3.0 - 4.5 |
| Nitrogen | 0.24 - 0.32 | 0.24 - 0.35 |
| Manganese | 1.20 max | 2.00 max |
| Silicon | per ASTM A182 | 1.00 max |
| Phosphorus | per ASTM A182 | 0.035 max |
| Sulphur | per ASTM A182 | 0.015 max |
| PREN | 41 - 43 typical | 40 minimum |
PREN is calculated as %Cr + 3.3 x %Mo + 16 x %N. A value of 40 or above separates super duplex from standard 22% Cr duplex such as S31803 and S32205, which fall in the 33 to 36 range.
Mechanical Properties
| Property | ASTM A182 F53 forgings | EN 1.4410 bar up to 160 mm |
|---|---|---|
| Tensile strength | 795 MPa (116 ksi) min | 730 - 930 MPa (106 - 135 ksi) |
| 0.2% proof strength | 550 MPa (80 ksi) min | 530 MPa (77 ksi) min |
| Elongation | 15% min | 25% min |
| Hardness | 310 HBW max (32 HRC) | 290 HB max |
| Impact energy | commonly specified at -46 C | 100 J (74 ft.lb) |
| Ferrite content | 40 - 60% | approx. 50:50 phase balance |
Notch ductility stays good down to about minus 50 C, which is why the grade is accepted for sub-zero offshore duty.
Typical physical properties, 1.4410
| Property | Value | Condition |
|---|---|---|
| Density | 7.8 kg/dm3 | 20 C |
| Modulus of elasticity | 200 GPa | 20 C |
| Thermal conductivity | 15 W/m.K | 20 C |
| Mean coefficient of thermal expansion | 13.0 x 10-6 /K | 20 - 100 C |
| Specific heat capacity | 500 J/kg.K | 20 C |
| Electrical resistivity | 0.80 ohm.mm2/m | 20 C |
| Magnetisable | Yes | ferritic phase present |
Corrosion Performance and the F51 Comparison
Most buyers are really deciding whether standard duplex 2205 will do the job or whether the project needs super duplex. Chloride level, operating temperature and H2S partial pressure settle it.
| Property | F51, UNS S31803 / S32205 | F53, UNS S32750 |
|---|---|---|
| PREN | 34 - 36 | 41 - 43 |
| Critical pitting temperature | 35 - 45 C | 55 - 70 C |
| Minimum yield strength | 450 MPa (65 ksi) | 550 MPa (80 ksi) |
| Chloride SCC limit | approx. 100 C | approx. 130 C |
| Seawater service | Ambient temperature only | Up to approx. 50 C |
| Relative material cost | Baseline | +30 to 50% |
Specify F53 when the process fluid carries chlorides above roughly 40 C, when sour gas conditions under NACE MR0175 call for PREN above 40, or when subsea valve bodies and wellhead components see warm produced water at high salinity. Maximum continuous service temperature is about 315 C (600 F). Above that, sigma phase and 475 C embrittlement cut toughness permanently.
Heat Treatment, Forming and Machining
S32750 has to be solution annealed and quenched after any hot or cold forming step. The annealing range is 1025 to 1125 C, with roughly 1050 C (1925 F) as the usual floor, followed immediately by a rapid water quench or forced air quench. Slow cooling through the 600 to 1000 C band precipitates sigma phase and destroys both toughness and pitting resistance, and no amount of later machining will recover it. Heat treated surfaces are pickled and rinsed before dispatch to restore full corrosion resistance.
On the machine, super duplex behaves nothing like an austenitic grade. High strength and a steep work hardening rate mean cutting speed has to come down substantially against 316 or 316L with coated carbide tooling, while feed is reduced only slightly. Rigid setups, positive geometry and uninterrupted cuts matter more than tool grade. Welding presents no particular difficulty provided heat input and interpass temperature are controlled to keep the phase balance.
UNS S32750 Forged Products We Make
Everything below is produced as open-die forgings or seamless rolled rings from EAF and VOD refined billet, with ESR remelted material available where the specification calls for it. We forge to customer drawing, to rough machined condition, or to finish machined parts.
- Seamless rolled rings and forged rings, including bearing rings, retaining rings, spacers and large diameter ring blanks
- Forged flanges: weld neck, blind, slip-on, orifice, long weld neck and special drilled patterns to ASME B16.5, B16.47 or drawing
- Forged round bars, blocks and billets, rough turned or peeled and ultrasonically tested
- Forged discs and tube sheets for heat exchangers, plus blind discs and cover plates
- Forged shafts, spindles, eccentric shafts and crankshafts for pumps, compressors and turbines
- Forged sleeves, bushings, hollow bars, tubes and pipes, trepanned or bored
- Forged valve components: valve stems, bodies, seat rings, blocks and bonnets for ball, gate, globe, check and plug valves
- Forged nozzles, manifolds, gears, wheels and rolls to drawing
See the full range of forged products or browse the other stainless steel forging grades.
Where UNS S32750 Forgings Are Used
Offshore oil and gas
Subsea and deepwater production systems, wellhead and manifold flanges, christmas tree components, chokes, connectors, bolting and downhole equipment.
Seawater and ballast systems
Seawater injection pumps, firewater and ballast piping, cooling water systems, service water pump shafts and sleeves.
Chemical and petrochemical
Heat exchangers, separators, pressure vessels, piping, tube sheets and flanges in hot chloride brine, ferric chloride and concentrated seawater.
Desalination
High pressure reverse osmosis components, energy recovery devices and seawater piping forgings.
Pulp and paper
Digesters, liquor tanks, bleaching plant hardware and paper machine parts exposed to chloride bearing liquors.
Power and rotating equipment
FGD systems, gas compressors, industrial air and nitrogen generators, gearboxes, turbine and power transmission shafting.
Testing, Inspection and Certification
Super duplex punishes poor thermal practice, and a tensile test on its own will not catch the problem. Our release package therefore covers microstructure and corrosion behaviour as well as chemistry and mechanicals.
| Test | Standard or method | Purpose |
|---|---|---|
| Ultrasonic examination | EN 10228-3, SEP 1921, ASTM A388 | Internal soundness |
| Liquid penetrant | ASTM E165 or client specification | Surface discontinuities |
| Corrosion test | ASTM A923 Method C, ferric chloride at 50 C | Detects intermetallic phase |
| Ferrite content | Point count or Feritscope, 40 - 60% | Phase balance |
| Charpy V-notch impact | Commonly at -46 C | Low temperature toughness |
| Hardness | 310 HBW / 32 HRC max | Sour service compliance |
| Material certificate | EN 10204 3.1 or 3.2 | Traceability, third party inspection on request |
Frequently Asked Questions
What is UNS S32750 equivalent to?
UNS S32750 is equivalent to ASTM A182 F53 in forged product form and to EN 1.4410 / X2CrNiMoN25-7-4 under EN 10088-3. It is commonly sold as Super Duplex 2507 or SAF 2507. The cast counterpart is ASTM A995 Grade 5A, and the grade is listed in NORSOK MDS D51 to D55, D57 and D58, and in NACE MR0175 / ISO 15156 for sour service.
What is the PREN of UNS S32750?
UNS S32750 is supplied with a PREN of at least 40, with typical values of 41 to 43. PREN is calculated as %Cr + 3.3 x %Mo + 16 x %N. The threshold of 40 is what separates super duplex from standard 22% Cr duplex, which sits at 33 to 36.
What is the difference between A182 F51 and A182 F53?
F51 is standard duplex 2205 (UNS S31803 or S32205), with PREN 34 to 36, a critical pitting temperature of 35 to 45 C and a minimum yield strength of 450 MPa. F53 is super duplex 2507 (UNS S32750), with PREN 41 to 43, a critical pitting temperature of 55 to 70 C and a minimum yield strength of 550 MPa, at roughly 30 to 50 percent higher material cost. F53 is specified when chlorides exceed about 40 C or when sour service requires PREN above 40.
What are the mechanical properties of ASTM A182 F53 forgings?
Solution annealed A182 F53 forgings require a minimum tensile strength of 795 MPa (116 ksi), a minimum 0.2% yield strength of 550 MPa (80 ksi), minimum elongation of 15% and a maximum hardness of 310 HBW (32 HRC), with ferrite between 40 and 60%. EN 1.4410 bar up to 160 mm is specified differently: 730 to 930 MPa tensile, 530 MPa minimum proof strength, 25% elongation, 290 HB maximum and 100 J impact energy.
How is UNS S32750 heat treated after forging?
It is solution annealed between 1025 and 1125 C, with roughly 1050 C (1925 F) as the usual minimum, then quenched immediately in water or by rapid forced air. Slow cooling lets sigma and other intermetallic phases precipitate, which severely reduces impact toughness and pitting resistance. Pickling and rinsing after heat treatment restores full corrosion resistance.
What is the maximum service temperature of super duplex 2507?
About 315 C (600 F) for continuous service. Above that range, prolonged exposure causes sigma phase formation and 475 C embrittlement, both of which permanently reduce ductility and corrosion resistance. At the cold end, notch ductility stays good down to about minus 50 C, and Charpy testing at minus 46 C is frequently specified for offshore work.
Is UNS S32750 magnetic?
Yes. Roughly half the microstructure is ferrite, so the alloy is magnetisable, unlike fully austenitic grades such as 316L or 904L. This is normal for duplex and super duplex steels and does not indicate wrong material.
Can Jiangyin Jiangnan Metal supply UNS S32750 forgings to drawing?
Yes. Jiangyin Jiangnan Metal Co., Ltd. manufactures UNS S32750 open-die forgings and seamless rolled rings to customer drawing or to standard dimensions, covering rings, flanges, bars, discs, tube sheets, shafts, sleeves, bushings and valve components. Material is EAF and VOD refined with ESR remelting available, supplied solution annealed and quenched with EN 10204 3.1 or 3.2 certification. Send a drawing to sales@steelforgepieces.com or call 0086-189-2135-9659.
Request a Quotation for UNS S32750 Forgings
Send the drawing, or just the outside diameter, inside diameter, height or length and the quantity. You will get price, forged weight, lead time and the proposed test and certification scope.
Jiangyin Jiangnan Metal Co., Ltd. · No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
- ASTM A182 / A182M, standard specification for forged or rolled alloy and stainless steel pipe flanges, forged fittings, and valves and parts for high temperature service.
- EN 10088-3, stainless steels, technical delivery conditions for semi-finished products, bars, rods and sections, grade 1.4410 X2CrNiMoN25-7-4.
- Smiths Metal Centres, UNS S32750 / 1.4410 / F53 technical datasheet, 2023 (EN 10088-3 mechanical and physical property data).
- ProjectMaterials, ASTM A182 Grade F53 technical summary (A182 F53 mechanical limits, PREN, critical pitting temperature, F51 comparison).
- NORSOK MDS D51 to D55, D57, D58, and NACE MR0175 / ISO 15156 for sour service limits.
Values are given for guidance. The purchase order specification and the mill test certificate always take precedence.
Related Grades
Also forged here in the duplex, super austenitic and precipitation hardening families: A182 F51, A182 F53, A182 F55, A182 F61, 904L, Sanicro 28, Alloy 24, 17-4PH, 15-5PH, Nitronic 50, Incoloy 825, Inconel 625.
Prepared by the technical sales team of Jiangyin Jiangnan Metal Co., Ltd., an open-die forging manufacturer in Jiangyin, Jiangsu, China.
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