1.4507 Super Duplex Stainless Steel Forgings (X2CrNiMoCuN25-6-3 / UNS S32550 / ASTM A182 F61)
Open-die forged rolled rings, flanges, shafts, disks, sleeves, tube sheets and bars. Solution annealed, ultrasonically tested, supplied with EN 10204 3.1 or 3.2 certification.
1.4507 is a copper-bearing super duplex stainless steel. Its EN designation is X2CrNiMoCuN25-6-3, it cross-references to UNS S32550 and UNS S32520, the ASTM forging grade is A182 F61, and it is widely known by the trade name Ferralium® 255. A nominal 25 % chromium, 3–4 % molybdenum, 1.5–2.5 % copper and 0.2 % nitrogen give it a PREN above 40, a minimum 0.2 % proof strength of 550 MPa (80 ksi), and strong resistance to seawater, sulphuric acid and phosphoric acid.
Jiangyin Jiangnan Metal Co., Ltd., an open-die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges 1.4507 to customer drawings: seamless rolled rings, flanges, shafts, round bars, disks, bushings, sleeves and tube sheets. All parts are solution annealed at 1080–1120 °C, water quenched, and certified to EN 10204 3.1 or 3.2. Enquiries: 0086-189-2135-9659, sales@steelforgepieces.com.
- EN designation
- 1.4507 / X2CrNiMoCuN25-6-3 (EN 10088-3, EN 10250-4)
- UNS numbers
- S32550 (Ferralium® 255) and S32520 (UR 52N+), closely related Cu-bearing super duplex grades
- ASTM forging grade
- A182 F61 (forgings), A479 S32550 (bar)
- Microstructure
- Duplex, roughly 50 % ferrite and 50 % austenite, normally controlled to 35–55 % ferrite
- PREN
- Above 40, calculated as %Cr + 3.3 × %Mo + 16 × %N
- Minimum Rp0.2
- 550 MPa / 80 ksi (ASTM A182 F61, A479 S32550)
- Density
- 7.81 g/cm³ (0.282 lb/in³)
- Delivery condition
- Solution annealed 1080–1120 °C (1975–2050 °F), rapid water quench
- Maximum service temperature
- About 250 °C (480 °F) continuous, limited by 475 °C embrittlement
- Manufacturer
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
What is 1.4507 super duplex stainless steel?
1.4507 is a ferritic-austenitic stainless steel with enough alloy content to sit in the super duplex class, which is defined as duplex grades reaching a pitting resistance equivalent number (PREN) of 40 or above. The microstructure is a roughly equal mixture of ferrite and austenite. That mixture is what gives duplex steels their usual pairing of high strength with high chloride corrosion resistance.
The feature that sets 1.4507 apart from the other super duplex grades is a deliberate copper addition of 1.5 to 2.5 %. Copper improves behaviour in reducing acids, above all sulphuric, phosphoric and several organic acids, where chromium and molybdenum on their own do less. The grade was developed in the United Kingdom during the 1960s and is still specified under its original trade name Ferralium® 255 as often as by its material number. Ferralium® is a registered trademark of Langley Alloys Ltd and appears here only to identify the grade.
A duplex microstructure is destroyed by uncontrolled heating, so 1.4507 is always supplied solution annealed and water quenched, and both the forging window and anything thermal that happens afterwards have to be kept under control. That makes the forging route, not just the chemistry on the mill certificate, the thing that decides whether the finished part performs to specification.
1.4507 equivalent grades and cross-reference
| Standard or system | Designation | Notes |
|---|---|---|
| EN 10088-1 / 10088-3 | 1.4507, X2CrNiMoCuN25-6-3 | Bars, rods, sections, semi-finished products |
| EN 10250-4 | 1.4507 | Open-die forgings, stainless steels |
| EN 10222-5 | 1.4507 | Forgings for pressure purposes |
| UNS | S32550, S32520 | S32550 is Ferralium® 255, S32520 is UR 52N+. Closely related, with slightly different limits |
| ASTM / ASME forgings | A182 F61, SA-182 F61 | Flanges, fittings, valves and parts for pressure service |
| ASTM bar | A479 S32550 | Bar and shapes. Seamless rolled rings are normally ordered to A182 F61 or to a client specification |
| Common trade names | Ferralium® 255, Alloy 255, UR 52N+ | Trademarks of their respective owners, quoted for identification only |
| JIS | No direct equivalent | ISO 15510 lists no JIS grade against S32550 or 1.4507. SUS 329J4L is a different, copper-free duplex grade and is not a substitute |
| China GB | 03Cr25Ni6Mo3Cu2N (nearest) | Nearest Chinese designation |
Chemical composition of 1.4507
The European and American specifications for this grade are similar but not identical, and the differences matter when a drawing cites one and a mill certificate the other. EN 10088-3 is tighter on carbon, silicon and sulphur and calls for a distinctly higher nickel band, 6.0 to 8.0 % against 4.5 to 6.5 %. ASTM A182 F61 and A479 S32550 are tighter on manganese but allow a wider chromium range and a lower minimum nitrogen. Orders normally go against one standard or the other. Where a customer needs a single heat to satisfy both, we hold the aim analysis inside the overlap of the two windows.
| Element | Minimum | Maximum |
|---|---|---|
| Carbon (C) | — | 0.030 |
| Silicon (Si) | — | 0.70 |
| Manganese (Mn) | — | 2.00 |
| Phosphorus (P) | — | 0.035 |
| Sulphur (S) | — | 0.015 |
| Chromium (Cr) | 24.0 | 26.0 |
| Nickel (Ni) | 6.0 | 8.0 |
| Molybdenum (Mo) | 3.0 | 4.0 |
| Copper (Cu) | 1.00 | 2.50 |
| Nitrogen (N) | 0.20 | 0.30 |
| Iron (Fe) | Balance | |
| Element | Minimum | Maximum |
|---|---|---|
| Carbon (C) | — | 0.04 |
| Silicon (Si) | — | 1.00 |
| Manganese (Mn) | — | 1.50 |
| Phosphorus (P) | — | 0.04 |
| Sulphur (S) | — | 0.03 |
| Chromium (Cr) | 24.0 | 27.0 |
| Nickel (Ni) | 4.5 | 6.5 |
| Molybdenum (Mo) | 2.9 | 3.9 |
| Copper (Cu) | 1.50 | 2.50 |
| Nitrogen (N) | 0.10 | 0.25 |
| Iron (Fe) | Balance | |
Values are the specification limits of the standards named in each caption. Product analysis tolerances apply as defined in the relevant standard. Always order against a stated specification and revision.
PREN of 1.4507, worked calculation
The pitting resistance equivalent number is the standard single-figure index for comparing resistance to chloride pitting. Taking the usual formula and the nominal mid-range analysis of 1.4507 at 25.0 % Cr, 3.5 % Mo and 0.22 % N:
PREN = %Cr + 3.3 × %Mo + 16 × %N = 25.0 + (3.3 × 3.5) + (16 × 0.22) = 25.0 + 11.55 + 3.52 = 40.1
A PREN of 40 is the accepted threshold for the super duplex class, and anything above roughly 32 is generally treated as suitable for ambient-temperature seawater. Per-heat values for 1.4507 usually land between 40 and 42. Where a project specification sets a minimum PREN, we select the heat to suit and state the calculated value on the material certificate.
Mechanical properties of 1.4507 forgings
| Property | Metric | Imperial | Basis |
|---|---|---|---|
| Tensile strength, Rm, min | 760 MPa | 110 ksi | ASTM A182 F61 / A479 S32550 |
| 0.2 % proof strength, Rp0.2, min | 550 MPa | 80 ksi | ASTM A182 F61 / A479 S32550 |
| Elongation A, min | 15 % | 15 % in 2 in | ASTM A182 F61 |
| Reduction of area, min | 45 % | 45 % | ASTM A182 F61 |
| Hardness, max | 297 HBW, typically 240 to 290 HBW as solution annealed | ASTM A182 F61 | |
| Typical proof strength achieved | about 586 MPa | about 85 ksi | Typical for the grade |
| Charpy V-notch impact, common project requirement | 45 J average at −46 °C, min | 33 ft·lb at −50 °F, min | NORSOK M-630 / M-650 style requirements |
| Ferrite content | 35 to 55 % by ASTM E562 point count | Typical duplex acceptance band | |
The impact and ferrite rows describe requirements end users commonly impose on super duplex forgings rather than minima inherent to the grade. They are quoted and tested when the enquiry calls for them. Properties are measured on test material representing the forging, heat treated together with the production parts.
For context, the 550 MPa minimum proof strength of 1.4507 is more than double that of 316L, whose minimum 0.2 % proof strength runs about 170 to 220 MPa depending on product form and standard. That is the reason designers reach for this grade to cut wall thickness and component weight in seawater and acid service, not only to gain corrosion resistance. Within the super duplex family 1.4507 is known for its high yield strength, which allows thinner sections for the same duty.
Physical properties of 1.4507
| Property | Value |
|---|---|
| Density | 7.81 g/cm³ (0.282 lb/in³) |
| Modulus of elasticity | about 200 GPa (29 × 10⁶ psi) |
| Mean coefficient of thermal expansion, 20 to 100 °C | about 11.1 × 10⁻⁶ K⁻¹ |
| Thermal conductivity | about 14 W/(m·K) |
| Specific heat capacity | about 480 J/(kg·K) |
| Electrical resistivity | about 0.85 µΩ·m |
| Magnetic response | Ferromagnetic, because of the ferrite phase |
| Melting range | about 1400 to 1450 °C |
Typical values for design guidance. They are not guaranteed properties and do not replace the material certificate.
Corrosion resistance and service limits
1.4507 resists pitting and crevice corrosion in chloride-bearing environments including warm seawater, and it resists chloride stress corrosion cracking far better than austenitic 304 and 316, which become vulnerable above roughly 60 °C. The copper content extends that performance into reducing acids. The grade performs well in sulphuric, phosphoric and nitric acid, and in organic acids such as acetic and formic acid.
Suited to
- Seawater, brine and produced water
- Sulphuric and phosphoric acid service
- Acetic and formic acid
- Chloride environments where SCC rules out 316L
- Sour service when ordered to NACE MR0175 / ISO 15156-3
Service limits to respect
- Continuous service above about 250 °C risks 475 °C embrittlement
- Prolonged exposure between about 600 °C and 1000 °C precipitates sigma phase and destroys toughness
- Strongly reducing media, and hydrofluoric acid, should be avoided
- The low-temperature limit is normally set by impact qualification, commonly −46 °C
Forging and heat treatment of 1.4507
Melting and starting material
Our 1.4507 billet is produced by electric arc furnace melting with AOD or VOD refining, and by electroslag remelting where the order calls for improved cleanliness or larger forged cross-sections. Every heat comes with a ladle analysis, and product analysis is taken from the forging when the specification requires it.
Open-die forging practice
Super duplex steels have a narrow hot-working window and forge less readily than austenitic grades. We forge from roughly 1150 to 1230 °C and hold the finishing temperature above about 1000 °C. Reheats are scheduled rather than improvised, so that no part of the section gets worked down into the sigma-forming range. Reduction ratios are planned to close the cast structure through the full cross-section, which is why an open-die forged part beats a casting on toughness, fatigue life and through-thickness consistency.
Solution annealing
All 1.4507 forgings are solution annealed at 1080 to 1120 °C (1975 to 2050 °F), then water quenched as fast as the section thickness allows. This dissolves sigma and other intermetallic phases formed during forging, re-dissolves chromium nitrides and carbides, and re-establishes the ferrite to austenite balance. Slow cooling through the critical range is the single most common cause of low impact values and failed corrosion tests on super duplex parts, so furnace charts are recorded and kept for every heat-treatment lot.
Welding and machining guidance
Welding
1.4507 welds by GTAW, SMAW, GMAW and SAW using super duplex consumables of the 25 9 4 type such as ER2594 or E2594, which carry extra nickel to restore austenite in the weld metal. Preheat is not used. Interpass temperature is normally kept below about 150 °C and heat input inside roughly 0.5 to 2.5 kJ/mm, so that the weld cools neither too fast, which leaves excess ferrite, nor too slowly, which precipitates intermetallics. Argon backing protects the root. Autogenous welding without filler is not recommended.
Machining
Expect machinability around 40 % of 304 stainless. The grade work-hardens quickly, so it wants rigid set-ups, sharp positive-rake carbide tooling, reduced surface speed, generous feed and constant flood coolant. The point is to keep the tool cutting under the hardened layer instead of rubbing on it. Where a part is to be delivered finish-machined, we normally rough machine, solution anneal, then finish, so that heat-treatment distortion comes off in the final cut.
1.4507 forged products and size ranges
Every item is forged to the customer's drawing or dimensional sketch. There is no catalogue minimum order quantity, and single prototype pieces are quoted alongside repeat production batches.
| Product form | Typical size range | Typical use |
|---|---|---|
| Seamless rolled rings | OD 200 to 2500 mm, height up to 600 mm | Valve seat rings, pump casings, flange rings, bearing races |
| Forged flanges | DN 15 to DN 1200, up to Class 2500 | Seawater and firewater piping, subsea manifolds |
| Forged round bars | Ø 60 to 600 mm, length up to 6000 mm | Shaft stock, fastener stock, machined valve parts |
| Forged shafts and stepped shafts | Ø 80 to 800 mm, length up to 6000 mm | Pump shafts, agitator shafts, eccentric shafts |
| Forged disks and blanks | Ø 100 to 1500 mm, thickness 20 to 400 mm | Blind flanges, closure plates, gear blanks |
| Forged sleeves and bushings | OD 100 to 1200 mm | Wear sleeves, bearing bushings, liner rings |
| Forged tube sheets | Up to Ø 2500 mm, thickness up to 300 mm | Heat exchangers, condensers, separators |
| Hollow forged tubes | OD 100 to 900 mm | Pressure vessel nozzles, cylinder bodies |
| Valve components | To drawing | Bodies, bonnets, stems, seat rings, gate and plug parts |
Size ranges indicate standard capability. Send a drawing with the finished dimensions, machining allowance and specification, and we will confirm feasibility, weight and price.
Where 1.4507 forgings are used
Oil, gas and subsea
Subsea manifolds, risers, wellhead and downhole components, seawater lift and firewater systems, pressure vessels and valve bodies. Specified for chloride SCC resistance combined with high strength.
Chemical and fertiliser plant
Phosphoric acid production, sulphuric acid handling, organic acid plant, pumps, agitator shafts, heat exchanger tube sheets and separator internals. The copper addition is the reason this grade gets picked over other super duplex steels here.
Power and FGD
Flue gas desulphurisation equipment, absorber and slurry pumps, spray headers and ducting components exposed to chloride-rich scrubber liquors.
Desalination and marine
High-pressure reverse osmosis trains, seawater piping and pump parts, propeller shafts and marine hardware.
Pulp, paper and mining
Digesters, bleach plant equipment, mineral processing pumps and slurry handling where abrasion and chloride attack occur together.
Rotating and pressure equipment
Compressor and turbine components, gearbox parts, shafts, sleeves and rolled rings for pressure-containing assemblies.
Testing, inspection and certification
| Test | Standard | Purpose |
|---|---|---|
| Chemical analysis | EN 10088-3 / ASTM A182 or A479 | Ladle analysis, plus product analysis on request. PREN stated on request |
| Tensile test | ISO 6892-1 / ASTM A370 | Rm, Rp0.2, elongation, reduction of area |
| Charpy V-notch impact | ISO 148-1 / ASTM A370 | Toughness at ambient or low temperature, commonly −46 °C |
| Ultrasonic testing | EN 10228-3, SEP 1921, ASTM A388 | Internal soundness of the forging |
| Liquid penetrant testing | EN ISO 3452 / ASTM E165 | Surface discontinuities |
| Ferrite determination | ASTM E562 | Phase balance after solution annealing |
| Intermetallic phase detection | ASTM A923 Method A / B / C | Confirms absence of harmful sigma phase |
| Pitting corrosion test | ASTM G48 Method A | Chloride pitting resistance at the specified test temperature |
| Sour service qualification | NACE MR0175 / ISO 15156-3 | Hardness and processing limits for H₂S environments |
| Duplex qualification package | ISO 17781, NORSOK M-630 / M-650 style | Quoted where the enquiry requires a qualified manufacturing route |
| Material certification | EN 10204 3.1 or 3.2 | 3.2 issued with third-party inspection by TÜV, BV, SGS, Lloyd's and similar |
Third-party witness inspection, positive material identification, dimensional reports and heat-treatment charts are supplied when the order specifies them. Marking, heat traceability and packing follow the customer's procedure where one has been issued.
1.4507 compared with other duplex and super duplex grades
| Grade | EN / UNS | Cr | Mo | Cu / W | N | PREN | Rp0.2 min | Distinguishing feature |
|---|---|---|---|---|---|---|---|---|
| 1.4507 | 1.4507 / S32550 | 25 | 3.5 | Cu 2 | 0.22 | 40 to 42 | 550 MPa | Copper addition, best of the group in sulphuric and phosphoric acid |
| 2205 | 1.4462 / S32205 | 22 | 3.1 | — | 0.17 | 35 | 450 MPa | Workhorse duplex, lower cost, not seawater-rated at elevated temperature |
| 2507 | 1.4410 / S32750 | 25 | 4.0 | — | 0.28 | 42 | 550 MPa | Highest Mo and N, no copper, general-purpose super duplex |
| F55 / Zeron 100 type | 1.4501 / S32760 | 25 | 3.6 | W 0.7, Cu 0.7 | 0.25 | 40 min | 550 MPa | Tungsten-bearing, frequently mandated by offshore specifications |
In practice the choice comes down to the medium. For chloride-only service, 2507 and S32760 are the usual picks. Where sulphuric, phosphoric or organic acids sit alongside the chlorides, the copper in 1.4507 is what buys the extra service life. We forge all four grades, so the recommendation we give is not limited by what happens to be in stock. See also A182 F51 (S31803), A182 F53 (S32750) and A182 F55 (S32760).
Request a quotation for 1.4507 forgings
Send a drawing or the finished dimensions and we will come back with weight, price and lead time. The more of the following you include, the faster and firmer the quotation:
- Product form and finished dimensions, or a drawing in PDF, DWG or STEP
- Specification and revision: EN 10088-3, ASTM A182 F61, A479 S32550, or a client specification
- Quantity, machining allowance and delivery condition, whether black forged, rough machined or finish machined
- Required testing: UT level, impact temperature, ASTM A923, G48, NACE MR0175, PMI
- Certification: EN 10204 3.1 or 3.2, and the inspection body if third-party witness is required
Jiangyin Jiangnan Metal Co., Ltd., open-die forging factory
No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Tel / WhatsApp / WeChat: 0086-189-2135-9659
Email: sales@steelforgepieces.com
Frequently asked questions about 1.4507
What is 1.4507 stainless steel?
1.4507 is a copper-bearing super duplex stainless steel with the EN designation X2CrNiMoCuN25-6-3. It holds about 25 % chromium, 3 to 4 % molybdenum, 1.5 to 2.5 % copper and 0.2 % nitrogen in a microstructure of roughly half ferrite and half austenite, which gives a PREN above 40 and a minimum proof strength of 550 MPa.
What is the UNS equivalent of 1.4507?
1.4507 cross-references to UNS S32550, known as Ferralium® 255, and UNS S32520, known as UR 52N+. The forging grade in ASTM A182 is F61, and bar is covered by ASTM A479 S32550. 1.4507 is not the same as UNS S32760 (F55) or UNS S32750 (F53), which are different super duplex grades.
Is 1.4507 the same as Ferralium 255?
Yes. Ferralium® 255 is the original trade name for the grade that carries the material number 1.4507 and the UNS number S32550. Ferralium® is a registered trademark of Langley Alloys Ltd. Material supplied to the 1.4507 or S32550 specification by other manufacturers meets the same standard requirements but is sold as 1.4507, S32550 or F61 rather than under the trademark.
What is the PREN of 1.4507, and is it seawater resistant?
Using PREN = %Cr + 3.3 × %Mo + 16 × %N with a nominal analysis of 25 % Cr, 3.5 % Mo and 0.22 % N, the PREN works out at about 40. Per-heat values usually fall between 40 and 42. Any grade above roughly 32 is generally considered resistant to ambient-temperature seawater, so 1.4507 suits seawater, brine and firewater service.
What is the difference between 1.4507 and 2205?
2205, which is 1.4462 or S32205, is a standard duplex grade with about 22 % chromium, 3.1 % molybdenum, no copper and a PREN near 35. 1.4507 carries higher chromium, higher nitrogen and a 2 % copper addition, which lifts the PREN above 40 and the minimum proof strength from 450 to 550 MPa. The practical difference shows up as service life in warm chloride and in acid media. 2205 remains the more economical choice where conditions are milder.
At what temperature is 1.4507 solution annealed?
1080 to 1120 °C, which is 1975 to 2050 °F, held long enough to equalise through the section, then quenched rapidly in water. Rapid cooling is what prevents sigma phase precipitation and the loss of toughness and corrosion resistance that comes with it. No intermediate stress-relief treatment is permitted.
Can 1.4507 be welded?
Yes. Use super duplex consumables of the 25 9 4 type such as ER2594 or E2594, no preheat, interpass temperature below about 150 °C, and heat input inside roughly 0.5 to 2.5 kJ/mm, with argon root backing. Post-weld heat treatment, if required at all, has to be a full solution anneal and water quench rather than a stress relief.
What is the maximum service temperature of 1.4507?
About 250 °C, or 480 °F, for continuous service. Above that, extended exposure near 475 °C embrittles the ferrite phase, and exposure between roughly 600 °C and 1000 °C forms sigma phase. Design codes normally impose the upper limit directly.
Is 1.4507 suitable for sour service?
1.4507 can be supplied for H₂S-containing service when ordered to NACE MR0175 / ISO 15156-3, which sets limits on hardness, ferrite balance and the manufacturing route, together with the partial pressure, chloride and temperature envelope in which the grade is qualified. State the sour-service requirement on the enquiry so that the melt source, heat treatment and testing are planned around it.
Who manufactures 1.4507 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 1.4507 (X2CrNiMoCuN25-6-3 / UNS S32550 / ASTM A182 F61) seamless rolled rings, flanges, shafts, bars, disks, sleeves and tube sheets to customer drawings, solution annealed and certified to EN 10204 3.1 or 3.2. Contact 0086-189-2135-9659 or sales@steelforgepieces.com.
What is the minimum order quantity and lead time for 1.4507 forgings?
There is no catalogue minimum order quantity, and single pieces are forged to drawing. Lead time depends on billet availability, forging size and the testing scope. A typical range is 25 to 45 days from drawing approval for items made from stock billet, and longer where a dedicated heat or ESR material is needed. Confirm the current lead time with your enquiry.
- Document
- 1.4507 (X2CrNiMoCuN25-6-3 / UNS S32550 / ASTM A182 F61) super duplex stainless steel forgings, technical data
- Issued by
- Jiangyin Jiangnan Metal Co., Ltd., Jiangyin, Jiangsu, China
- Basis
- EN 10088-3, EN 10250-4, ASTM A182 and ASTM A479 requirements, together with our own production practice
- Last reviewed
- 23 September 2026
- Reference
- https://www.steelforgepieces.com/Stainless-Steel/1.4507.html
Figures given here are for guidance. The material certificate issued with each order governs.
Related grades we forge
- A182 F51 (1.4462 / S31803) duplex forgings, the standard duplex workhorse
- A182 F53 (1.4410 / S32750) super duplex forgings, 2507 type
- A182 F55 (1.4501 / S32760) super duplex forgings, tungsten-bearing
- A182 F44 (1.4547 / S31254) 6 % Mo austenitic forgings
- 904L (1.4539 / N08904) forgings, for strongly reducing acid service
- Alloy 20 (N08020) forgings, sulphuric acid specialist
- Sanicro 28 (N08028) forgings
- Forged tube sheets and forged disks