1.4501 Super Duplex Stainless Steel Forgings (UNS S32760 / ASTM A182 F55)
1.4501 is a super duplex stainless steel containing about 25% chromium, 7% nickel and 3.5% molybdenum, with copper and tungsten added. The European name for the grade is X2CrNiMoCuWN 25-7-4. The same alloy is covered by UNS S32760, and forgings in the grade are ordered to ASTM A182 Grade F55. Pitting Resistance Equivalent Number (PREN) is 40 minimum. Yield strength is around twice that of 316L. The grade is used in seawater, sour service and other chloride-bearing duty between −50 °C and +300 °C.
Key facts about 1.4501
- EN designation
- 1.4501 / X2CrNiMoCuWN 25-7-4 (EN 10088-3)
- UNS number
- S32760 wrought; J93380 / 1.4508 for the cast equivalent
- Forging specification
- ASTM A182 Grade F55; bar to ASTM A276 / A479; forging stock to ASTM A314
- Alloy family
- Super duplex, ferritic and austenitic, roughly 50:50 phase balance
- PREN
- 40 minimum, calculated as %Cr + 3.3 x %Mo + 16 x %N
- Yield strength
- 530 MPa (77 ksi) minimum to EN 10088-3; 550 MPa (80 ksi) minimum to ASTM A182 F55
- Service range
- −50 °C to +300 °C (−58 °F to +572 °F)
- Heat treatment
- Solution anneal 1100–1140 °C, immediate water quench
- Magnetic
- Yes, the ferrite phase makes 1.4501 ferromagnetic
- Density
- About 7.8 g/cm³ (0.282 lb/in³)
- Forged forms supplied
- Seamless rolled rings, flanges, round bars, discs, shafts, sleeves, bushings, tube sheets, hollow bars, valve bodies
- Manufacturer
- Jiangyin Jiangnan Metal Co., Ltd., No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin, Jiangsu, China
What is 1.4501 stainless steel?
1.4501 is the European material number for a 25% chromium super duplex stainless steel. EN 10088-3 lists it under the name X2CrNiMoCuWN 25-7-4. The microstructure holds ferrite and austenite in roughly equal proportions. Ferrite carries the strength and the resistance to chloride stress corrosion cracking. Austenite carries the toughness and the ductility. Together the two phases give the grade both high strength and high corrosion resistance.
1.4501 differs from the more common super duplex grade 2507 (UNS S32750) in two elements. It contains 0.5 to 1.0% tungsten, which improves crevice corrosion resistance, and 0.5 to 1.0% copper, which improves resistance to reducing acids such as sulphuric and phosphoric acid. For that reason 1.4501 is often chosen over 2507 for mixed-acid process duty. In pure seawater duty the two grades perform to a similar level.
The alloy is also sold under the trade name Zeron 100, a registered trademark of RA Materials. UNS S32760 defines a compositional range. Proprietary versions of the alloy are held to a narrower window inside that range. Material supplied to the generic 1.4501 / S32760 / F55 specification meets the requirements of those standards, including the PREN 40 minimum.
Chemical composition of 1.4501
| Element | Minimum % | Maximum % | Role in the alloy |
|---|---|---|---|
| Chromium (Cr) | 24.0 | 26.0 | Main contributor to the passive film and to PREN |
| Nickel (Ni) | 6.0 | 8.0 | Stabilises the austenite phase |
| Molybdenum (Mo) | 3.0 | 4.0 | Pitting and crevice corrosion resistance |
| Copper (Cu) | 0.50 | 1.00 | Resistance to reducing acids |
| Tungsten (W) | 0.50 | 1.00 | Crevice corrosion resistance |
| Nitrogen (N) | 0.20 | 0.30 | Strength, austenite stability, pitting resistance |
| Carbon (C) | – | 0.030 | Held low to avoid carbide precipitation |
| Manganese (Mn) | – | 1.00 | Deoxidiser |
| Silicon (Si) | – | 1.00 | Deoxidiser |
| Phosphorus (P) | – | 0.030 | Residual, restricted |
| Sulphur (S) | – | 0.010 | Residual, restricted for toughness |
| Iron (Fe) | Balance | Matrix | |
| PREN | 40.0 | – | %Cr + 3.3 x %Mo + 16 x %N |
PREN formula. The 40 minimum for 1.4501 is calculated as %Cr + 3.3 x %Mo + 16 x %N. Some project specifications use a tungsten-modified formula, %Cr + 3.3 x (%Mo + 0.5 x %W) + 16 x %N, which returns a higher figure for this grade. We report the actual PREN of every heat on the mill test certificate, calculated from the certified ladle analysis, and use whichever formula your specification names.
Mechanical properties of 1.4501 forgings
| Property | EN 10088-3, 1.4501, section up to 160 mm | ASTM A182 Grade F55 |
|---|---|---|
| 0.2% proof stress, Rp0.2 | 530 MPa (77 ksi) min | 550 MPa (80 ksi) min |
| Tensile strength, Rm | 730–930 MPa (106–135 ksi) | 750 MPa (109 ksi) min |
| Elongation, A | 25% min | 25% min |
| Hardness | 290 HB max | 290 HB max; 28 HRC max for NACE MR0175 service |
| Charpy V-notch, longitudinal | 100 J (74 ft·lb) min at room temperature | To purchase order, commonly 45 J min at −46 °C |
| Charpy V-notch, transverse | 60 J (44 ft·lb) min | To purchase order |
The values above apply to sections up to 160 mm. In heavier forgings the quench rate at the core is lower. If the core spends too long between 600 and 1000 °C, sigma phase forms and both impact energy and pitting resistance fall. On 1.4501 forgings over 200 mm section thickness we quench in agitated water and take test material from a prolongation representing the thickest section, so that the certified values come from the core condition and not from the surface.
Physical properties
| Property | Value |
|---|---|
| Density | About 7.8 g/cm³ (0.282 lb/in³) |
| Modulus of elasticity | About 200 GPa (29 x 10&sup6; psi) |
| Thermal expansion, 20–100 °C | About 13 x 10⁻⁶ /K |
| Thermal conductivity | About 15 W/m·K |
| Magnetic response | Ferromagnetic |
| Maximum continuous service temperature | 300 °C (572 °F) |
| Minimum design temperature | −50 °C (−58 °F) |
Temperature limit. 1.4501 is not suitable for continuous service above 300 °C. Long exposure above that temperature causes alpha-prime (475 °C) embrittlement, and at higher temperatures sigma phase forms. Both reduce toughness sharply. For continuous high-temperature duty, specify a nickel alloy such as Alloy 625 or Alloy 825.
1.4501 equivalent grades and specifications
| System | Designation | Product scope |
|---|---|---|
| EN / Werkstoff | 1.4501, X2CrNiMoCuWN 25-7-4 | EN 10088-3 bar, EN 10088-2 plate, EN 10222-5 forgings |
| UNS | S32760 wrought, J93380 cast | All wrought forms |
| ASTM, forgings | A182 Grade F55 | Forged flanges, fittings, valves, pressure parts |
| ASTM, bar | A276, A479 | Bars and shapes |
| ASTM, forging stock | A314 | Billet for forging |
| ASTM, plate and sheet | A240 | Plate, sheet, strip |
| ASTM, pipe and tube | A790, A789, A928 | Seamless and welded pipe and tube |
| ASTM, castings | A890 / A995 Grade 6A (1.4508) | Cast equivalent, not interchangeable with forgings |
| NORSOK | MDS D51 to D58, manufacturer qualification to M-650 | Offshore piping and forged components |
| Sour service | NACE MR0175 / ISO 15156-3 | Oil and gas service containing H₂S |
| Pressure codes | ASME B16.5, B16.34, B16.47, B31.3; API 6A; API 5LC | Flange and valve dimensional standards |
| Trade name | Zeron 100, registered trademark of RA Materials | Cross-reference only, not a supply designation |
How 1.4501 compares with neighbouring grades
| Grade | Type | Typical PREN | Min. yield | Chosen instead of 1.4501 when |
|---|---|---|---|---|
| 1.4501 / S32760 / F55 | Super duplex with Cu and W | 40 and above | 530–550 MPa | – |
| 1.4410 / S32750 / F53 (2507) | Super duplex | 41 and above | 550 MPa | Pure seawater duty, or wider stock availability is needed |
| 1.4462 / S31803 / S32205 / F51 | Standard duplex, 22Cr | 34–36 | 450 MPa | The duty is less aggressive and cost matters more |
| 1.4539 / N08904 (904L) | Super austenitic | 34–36 | 220 MPa | A fully austenitic, non-magnetic structure is required |
| N08825 (Alloy 825) | Nickel alloy | – | 241 MPa | Service runs above 300 °C, or acids are strongly reducing |
| 1.4404 / 316L / F316L | Austenitic 18-8 | 24–26 | 170 MPa | There is no chloride exposure and cost is the deciding factor |
1.4501 has roughly three times the yield strength of 316L and about twice that of 904L, which normally allows thinner sections and lighter components at the same pressure rating. Against 2507 the corrosion class is the same, since both are PREN 40 and above. The copper and tungsten in 1.4501 are what separate the two, and they favour 1.4501 in reducing acids and in crevice-prone geometry.
Corrosion resistance and testing
1.4501 resists pitting and crevice corrosion in chloride environments, chloride stress corrosion cracking, and general corrosion in a wide range of organic and inorganic acids. In the ASTM G48 Method A ferric chloride test, solution-annealed wrought material normally shows a critical pitting temperature of 70 to 80 °C, depending on product form and production route.
For offshore work the acceptance test is usually ASTM G48 Method A at 50 °C for 24 hours, as required by NORSOK M-630. Acceptance is no pitting at 20x magnification and weight loss under 4.0 g/m². Material that fails this test has almost always been heat treated incorrectly. What the test detects is intermetallic phase formed by a low solution annealing temperature or a slow quench, not a shortage of alloying elements.
Tests we perform on 1.4501 forgings
Chemical analysis
OES and combustion analysis of the ladle sample, with PREN calculated and stated on the certificate.
Tensile and impact
ASTM A370 or ISO 6892, with Charpy V-notch at −46 °C or as specified.
Ferrite content
ASTM E562 point count, typically 40 to 60% ferrite, or to the 35 to 55% window many project specifications require.
Intermetallic phase
ASTM A923 Method A, B or C to confirm the absence of sigma, chi and secondary austenite.
Pitting corrosion
ASTM G48 Method A, 24 hours, at 50 °C or at the temperature your specification names.
Ultrasonic testing
EN 10228-3, SEP 1921 or ASTM A388 to the acceptance class on your order.
Hardness
Brinell or Rockwell, including the 28 HRC ceiling for NACE MR0175 sour service.
PMI
Positive material identification on finished parts before shipment.
How we forge and heat treat 1.4501
Melting is by electric arc furnace with AOD or VOD refining. Electroslag remelting is available where a specification calls for it, or where the section size and the cleanliness requirement justify it. Forging runs between 1100 and 1230 °C. Final reduction finishes above 950 °C so that the ferrite and austenite balance is held through the last pass.
After forging, parts are cooled below 538 °C before heat treatment. They are then solution annealed at 1100 to 1140 °C and quenched immediately in agitated water. The quench carries the full section through the 600 to 1000 °C range before sigma or chi phase can form. Air cooling is not an acceptable substitute. In heavy sections the quench rate is the usual cause of low Charpy values and failed G48 tests.
Machining 1.4501
1.4501 work hardens quickly and needs different tooling data from the austenitic grades. Against machinability-improved 316/316L, cutting speed should come down by about 50 to 55% when turning 1.4501 with coated cemented carbide tools. Feed rates should be reduced only slightly, because a light feed causes rubbing instead of cutting and speeds up work hardening. Rigid setups, sharp tooling, positive rake geometry and high coolant volume are all needed. Similar reductions apply to drilling and milling.
1.4501 forged products we manufacture
We produce 1.4501 components to customer drawings as open-die forgings and seamless rolled rings, supplied rough machined or finish machined. Typical forms are listed below.
Seamless rolled rings
Ring-rolled 1.4501 for flanges, bearing races, valve seats and vessel courses.
Forged flanges
Weld neck, slip-on, blind and threaded flanges to ASME B16.5 and B16.47.
Round bars and billets
Forged bar for machining into valve stems, fasteners and shafts.
Discs and blanks
Forged discs for tube sheets, closures, blind covers and pump components.
Shafts and spindles
Pump shafts, propeller shafts, eccentric shafts and turbine spindles.
Sleeves and bushings
Hollow forgings and bored sleeves for compressor and pump service.
Tube sheets
Heat exchanger tube sheets and baffle plates from forged plate stock.
Valve components
Bodies, bonnets, seat rings, stems and blocks for ball, gate, globe, check and plug valves.
Size range
Size range depends on the product form and on the section thickness that can be through-quenched to hold the required ferrite balance. Send the drawing or the finished dimensions with your enquiry and we will confirm whether the part falls inside our range before we quote.
Where 1.4501 forgings are used
1.4501 is specified where chloride content, pressure and strength requirements together rule out the austenitic stainless steels, and where service temperature stays below 300 °C.
- Offshore oil and gas: subsea manifolds, wellhead and christmas tree components, risers, chokes, connectors, seawater injection systems, firewater pipework.
- Desalination: high-pressure reverse osmosis plant, energy recovery devices, seawater piping, pump casings.
- Chemical and petrochemical processing: pumps, valves, heat exchanger tube sheets, pressure vessel components, separator internals handling mixed chloride and acid streams.
- Marine: propeller shafts, rudder stocks, shaft seals, seawater pumps, chemical tanker cargo systems.
- Pulp and paper: digesters, liquor tanks, bleach plant equipment, paper machine components.
- Power generation: flue gas desulphurisation equipment, absorber components, cooling water systems.
- Mining and metallurgy: pressure oxidation autoclaves, slurry pumps, acid-handling equipment.
- Rotating equipment: industrial air compressors, gas compressors, gearbox shafts, nitrogen generator components.
How to specify 1.4501 forgings on an enquiry
A quotation moves faster when the enquiry carries the following information. In most cases a drawing covers all of it.
- The grade and specification: 1.4501, UNS S32760 or ASTM A182 F55, plus any project specification such as NORSOK MDS D57 or NACE MR0175 / ISO 15156.
- Product form and dimensions: ring, flange, disc, bar or shaft, with outside diameter, inside diameter, height or length, and whether the part is rough machined or finish machined.
- Quantity and required delivery date.
- Testing requirements: impact test temperature, ASTM G48 test temperature, ferrite range, ASTM A923 method, ultrasonic acceptance class.
- Certification: EN 10204 Type 3.1, or Type 3.2 with third-party witness such as DNV, BV, LR, TUV or SGS.
- Marking and traceability: heat number, heat treatment lot, purchase order reference.
Send drawings or specifications to sales@steelforgepieces.com or call +86 189-2135-9659.
Frequently asked questions about 1.4501
What is 1.4501 equivalent to?
1.4501 is equivalent to UNS S32760 and, for forgings, to ASTM A182 Grade F55. Its full EN name is X2CrNiMoCuWN 25-7-4. Bar is ordered to ASTM A276 or A479, plate to ASTM A240, and pipe to ASTM A790. The cast version of the same alloy is UNS J93380 / EN 1.4508, covered by ASTM A890 / A995 Grade 6A, which is a different product and is not interchangeable with forgings.
Is 1.4501 the same as Zeron 100?
They cover the same alloy. Zeron 100 is a registered trade name of RA Materials for a proprietary version of UNS S32760, held to a narrower compositional window than the S32760 specification requires. Material supplied as 1.4501 / S32760 / F55 meets the published specification, including the PREN 40 minimum. If your project documentation names a proprietary product rather than the generic specification, tell us at enquiry stage so that the correct material is sourced.
Is 1.4501 magnetic?
Yes. 1.4501 has a duplex microstructure holding roughly 40 to 60% ferrite, and ferrite is ferromagnetic. Unlike the austenitic grades such as 316L or 904L, 1.4501 is attracted to a magnet in the solution-annealed condition. Where a non-magnetic material is required, a fully austenitic grade has to be specified instead.
What is the PREN of 1.4501?
The specification requires 40 minimum, calculated as %Cr + 3.3 x %Mo + 16 x %N. Actual heats normally fall between 40 and 42. PREN of 40 and above is the threshold most offshore specifications use for seawater-wetted surfaces, and some sour-service applications require 41 minimum. The actual PREN of each heat is stated on our mill test certificate.
What is the maximum service temperature of 1.4501?
300 °C (572 °F) for continuous service. Above that temperature 1.4501 loses toughness through alpha-prime embrittlement, and at higher temperatures sigma phase forms. The minimum design temperature is normally taken as −50 °C. For duty outside that window, a nickel alloy or an austenitic grade is the appropriate substitution.
What heat treatment does 1.4501 require?
Solution annealing at 1100 to 1140 °C followed by an immediate water quench. After hot working, forgings are first cooled below 538 °C before the solution treatment. The quench has to be fast enough to move the full section through the 600 to 1000 °C range before sigma or chi phase can form. Air cooling is not an acceptable substitute, and it is the most common cause of failed Charpy impact and ASTM G48 corrosion tests on super duplex forgings.
How does 1.4501 compare with 2507 (UNS S32750)?
Both are super duplex grades with PREN 40 and above and similar strength. What separates them is the deliberate copper (0.5 to 1.0%) and tungsten (0.5 to 1.0%) content of 1.4501. Copper improves resistance in reducing acids such as sulphuric and phosphoric; tungsten improves crevice corrosion resistance. In 2507, copper is restricted to a residual level and is not an intentional addition. For pure seawater service the two perform to a similar level and availability often decides. For mixed-acid process streams, 1.4501 is usually preferred.
Can 1.4501 be welded?
Yes, under a qualified welding procedure. Heat input has to be controlled to keep the ferrite and austenite balance in the weld metal and the heat-affected zone inside the required range, commonly 35 to 65 FN under NORSOK M-650. Matching or over-alloyed super duplex filler metal is used. Welded 1.4501 has a lower critical pitting temperature than the parent metal, so where a G48 acceptance test applies to welded assemblies the test temperature is normally reduced accordingly. Procedure qualification to ASME Section IX or EN ISO 15614-1 is required, including ferrite measurement in the weld.
Why is 1.4501 harder to machine than 316L?
It is roughly three times stronger and it work hardens quickly. Cutting speed has to come down by about 50 to 55% against machinability-improved 316/316L when using coated cemented carbide tooling. Feed rates should be reduced only slightly, since a light feed causes rubbing and speeds up work hardening. Rigid fixturing, sharp tools and high coolant volume are needed.
Does 1.4501 comply with NACE MR0175 for sour service?
1.4501 is listed in NACE MR0175 / ISO 15156-3 for sour service within defined limits on H₂S partial pressure, chloride content, temperature and pH. Hardness must not exceed 28 HRC and ferrite content has to sit inside the prescribed range. The applicable environmental limits are recorded on the EN 10204 Type 3.1 or 3.2 certificate. Confirm the service envelope on your enquiry so that the correct material condition and test scope are quoted.
Who manufactures 1.4501 forgings in China?
Jiangyin Jiangnan Metal Co., Ltd. is an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, producing 1.4501 / UNS S32760 / ASTM A182 F55 seamless rolled rings, flanges, bars, discs, shafts and sleeves to customer drawings, with EN 10204 3.1 and 3.2 certification and third-party witness inspection available. Enquiries: sales@steelforgepieces.com, +86 189-2135-9659.
Standards referenced on this page
- EN 10088-3, stainless steels: technical delivery conditions for semi-finished products, bars, rods and sections
- ASTM A182 / A182M, forged or rolled alloy and stainless steel pipe flanges, forged fittings and valves
- ASTM A276, A479, A314, A240, A790, bar, forging stock, plate and pipe product specifications
- ASTM G48 Method A, pitting and crevice corrosion resistance of stainless steels
- ASTM A923, detection of intermetallic phase in duplex stainless steels
- ASTM E562, determining volume fraction by systematic manual point count
- EN 10228-3, SEP 1921, ASTM A388, ultrasonic examination of forgings
- EN 10204, types of inspection documents for metallic products
- NORSOK M-630 and M-650, material data sheets and manufacturer qualification
- NACE MR0175 / ISO 15156-3, materials for use in H₂S-containing environments
Document control
- Document
- 1.4501 / UNS S32760 / ASTM A182 F55 technical datasheet
- Issued by
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
- Revision date
- 23 September 2026
- Reference
- https://www.steelforgepieces.com/Stainless-Steel/1.4501.html
- Basis
- EN 10088-3, ASTM A182, NORSOK M-630 and M-650, NACE MR0175 / ISO 15156-3. The governing standard takes precedence over this summary.
Request a quotation for 1.4501 forgings
Send a drawing or a specification and we will quote size, weight, testing scope and lead time.
Jiangyin Jiangnan Metal Co., Ltd., open-die forging factoryNo.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Phone, WhatsApp and WeChat: +86 189-2135-9659
Email: sales@steelforgepieces.com