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X2CrNiMoCuWN25-7-4 Super Duplex Forgings (EN 1.4501 / UNS S32760 / ASTM A182 F55)
Forged rings, seamless rolled rings, flanges, round bars, discs, sleeves, bushings, shafts, tube sheets and forged pipes, made to drawing by Jiangyin Jiangnan Metal Co., Ltd.
X2CrNiMoCuWN25-7-4 is the EN 10088 steel name for material number 1.4501, a tungsten and copper alloyed super duplex stainless steel with a microstructure of approximately 50 percent austenite and 50 percent ferrite. It is the same alloy as UNS S32760 and as the forging grade ASTM A182 F55, supplied with a pitting resistance equivalent number (PREN) of at least 40.
The grade carries high mechanical strength, typically up to about 600 MPa yield, together with good ductility and high resistance to pitting, crevice corrosion and chloride stress corrosion cracking in seawater and in oil and gas production environments. Notch ductility stays good down to minus 50 degrees C.
Jiangyin Jiangnan Metal Co., Ltd. forges this grade in Jiangyin, Jiangsu, China, as rings, rolled rings, flanges, bars, discs, sleeves, shafts, tube sheets and forged pipes, solution annealed and water quenched, with ultrasonic testing and EN 10204-3.1 or 3.2 certification. Enquiries to sales@steelforgepieces.com or +86-189-2135-9659.
- EN steel name
- X2CrNiMoCuWN25-7-4
- EN steel number
- 1.4501
- UNS number
- S32760
- ASTM forging grade
- A182 F55
- Steel type
- Super duplex, 50:50
- PREN
- 40 minimum
- Density
- 7.8 g/cm³
- Magnetic
- Yes
1. Designations and specifications
The grade is sold under several names depending on the issuing body. Every entry below describes the same 25 percent chromium super duplex stainless steel with tungsten and copper additions.
| EN 10088-1 name and number | X2CrNiMoCuWN25-7-4, 1.4501 |
|---|---|
| UNS | S32760 |
| ASTM forging designation | A182 F55 |
| Offshore material data sheets | NORSOK MDS D51 to D55, D57 and D58 |
| Sour service | NACE MR0175 / ISO 15156, current revision |
| Open die forgings | EN 10250-4 |
| Bars and semi-finished products | EN 10088-3, EN 10272 for pressure purposes |
| Plate and flat products | EN 10088-2, EN 10028-7 for pressure purposes |
| Tube and fittings | EN 10216-5, EN 10217-7, EN 10297-2, EN 10253-3, EN 10253-4 |
| Cross-referenced trade name | Zeron 100, trade name of the originating mill, listed as a cross-reference only |
2. Chemical composition
Limits in weight percent, balance iron. The tungsten and copper additions separate 1.4501 from the other 25 percent chromium super duplex grades. Tungsten contributes to pitting resistance, copper improves behaviour in mildly reducing acids.
| Limit | C | Si | Mn | P | S | Cr | Ni | Mo | Cu | W | N |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Min. | - | - | - | - | - | 24.0 | 6.0 | 3.0 | 0.50 | 0.50 | 0.20 |
| Max. | 0.030 | 1.00 | 1.00 | 0.035 | 0.015 | 26.0 | 8.0 | 4.0 | 1.00 | 1.00 | 0.30 |
PREN is quoted as 40 minimum using PREN = %Cr + 3.3 x %Mo + 16 x %N. With the tungsten corrected formula PREW = %Cr + 3.3 x (%Mo + 0.5 x %W) + 16 x %N, typical values run above 41.
Melting route
We melt and refine this grade by EAF plus VOD. An ESR remelted route is available where the customer specification or the end user approval calls for remelted material and tighter inclusion cleanliness.
3. Mechanical properties
Two acceptance sets are in common use, depending on the standard the order is placed against. State on the enquiry which one applies, because the yield and tensile minima differ.
| Property | EN 10088-3, 1.4501, up to 160 mm diameter | ASTM A182 F55 |
|---|---|---|
| 0.2 % proof strength, Rp0.2 | 530 MPa min. (77 ksi) | 550 MPa min. (80 ksi) |
| Tensile strength, Rm | 730 to 930 MPa (106 to 135 ksi) | 750 MPa min. (109 ksi) |
| Elongation, A | 25 % min. | 25 % min. |
| Hardness | 290 HB max. | 28 HRC max. where NACE MR0175 applies |
| Charpy V-notch impact energy | 100 J min. | Project dependent, low temperature testing commonly specified |
Values apply to the solution treated condition. The grade is not hardenable by heat treatment. Strength comes from the duplex microstructure and the nitrogen content, so section size and the effectiveness of the quench govern the result.
Physical properties
| Density | 7.8 kg/dm³ |
|---|---|
| Modulus of elasticity at 20 °C | 200 GPa |
| Thermal conductivity at 20 °C | 15 W/(m·K) |
| Mean thermal expansion, 20 to 100 °C | 13.0 x 10-6 /K |
| Specific heat capacity at 20 °C | 500 J/(kg·K) |
| Electrical resistivity at 20 °C | 0.80 Ω·mm²/m |
| Magnetisable | Yes |
4. Forging and heat treatment
Hot forming runs at roughly 1100 to 1280 degrees C. Published duplex fabrication guidance gives a hot working range for S32760 of about 1230 degrees C down to 1000 degrees C. Forging has to be followed by a full solution anneal, since hot work alone does not restore the balanced microstructure.
- Solution annealing. Approximately 1100 to 1140 degrees C, soak proportional to section thickness, then an immediate rapid water quench to room temperature.
- Why the quench matters. Slow cooling through roughly 600 to 1000 degrees C lets sigma phase, chi phase and chromium nitrides form in the ferrite, which cuts both impact toughness and corrosion performance. Long exposure in that band is avoided in service and in any post-forging operation.
- Verification. Intermetallic phase to ASTM A923, ferrite balance by point counting to ASTM E562, and pitting resistance by ASTM G48 critical pitting temperature testing where the project specification calls for it.
Machining and welding
Machining and welding of this super duplex grade present no particular problems when correct practice is followed, and detailed guidance is available on request. The high yield strength and work hardening behaviour call for rigid set-ups, sharp tooling and reduced cutting speeds compared with 316 and 316L. We can supply the machining parameters we run in-house along with the quotation.
5. Corrosion resistance and grade selection
With PREN of 40 minimum the grade gives high resistance to pitting, to crevice corrosion and to stress corrosion cracking, with good notch ductility at ambient and sub-zero temperatures down to minus 50 degrees C. It resists seawater and suits service in sulphuric acid.
On that basis it is used as an alternative to 300 series austenitic grades such as type 316, to standard 22 percent chromium duplex steel and to precipitation hardening stainless steels. Where appropriate it can also be considered in place of more costly Grade 5 titanium or nickel based alloys. It is not stronger than every super duplex grade: against UNS S32750 / 2507 the tensile minimum is lower, 750 MPa against 795 MPa, while the tungsten and copper additions of 1.4501 target chloride and reducing acid performance. Confirm final grade selection against the project corrosion specification.
6. Forged products in X2CrNiMoCuWN25-7-4
Every item below is produced to customer drawing or specification at our Jiangyin works, in the solution annealed and water quenched condition.
Forged and seamless rolled rings
Ring rolled and open-die rings for bearing, seal and slewing applications, used in mining, marine, pharmaceutical, petrochemical and chemical engineering plant. See rolled rings.
Forged flanges
Weld neck, slip-on, blind, lap joint and integral flanges, plus flange forging blanks, for seawater, firewater and subsea pipework systems with risers and manifolds.
Round bars and billets
Forged bars for valve stems, spindles, fasteners and machined components. See forged bars.
Discs and blanks
Forged discs for pump, compressor and generator components, including subsea and deepwater production equipment. See forged discs.
Shafts and eccentric shafts
Pump and compressor shafts, spindles and power transmission components for corrosive and chloride bearing duty.
Sleeves, bushings and hollow bars
Forged sleeves and bushings for pumps, valves, chokes and downhole tooling assemblies.
Forged tubes, pipes and tube sheets
Tube sheets, forged pipe and heavy wall tubular blanks for separators, heat exchangers and pressure vessels.
Valve components
Valve bodies, bonnets, seat rings, blocks and stems for ball, gate, globe, check, plug and choke valves, strainers and manifold blocks.
Custom open-die forgings
Blocks, hubs, connectors, nozzles, manifolds, rolls and wheels, including desalination, reverse osmosis plant and flue gas desulphurisation components.
7. Typical applications
Typical duties for this grade cover pumps, valves, chokes, Xmas trees, pipework and flanges, bolting, connectors and manifolds in the oil and gas industry, along with equipment for the defence, chemical and marine industries. Our customers also use it for separator and heat exchanger parts, seawater and firewater systems, subsea production equipment, desalination and high pressure reverse osmosis plant, flue gas desulphurisation equipment, pulp and paper digesters and liquor tanks, and mining and metallurgical process equipment.
8. Testing, inspection and documentation
- Ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388, to the acceptance class stated on the order.
- Mechanical testing covering tensile, Charpy V-notch including low temperature, and hardness, with test location and orientation agreed before forging.
- Microstructure and corrosion testing covering ferrite content, intermetallic phase to ASTM A923 and ASTM G48 pitting tests on request.
- Certification to EN 10204-3.1, or EN 10204-3.2 with third party inspection by TUV, BV, SGS, LR or a customer nominated agency.
- Reports covering dimensional inspection, NDT, PMI, heat treatment charts and full material traceability with every shipment.
9. Frequently asked questions
What is X2CrNiMoCuWN25-7-4?
It is the EN 10088 steel name for material number 1.4501, a tungsten and copper alloyed super duplex stainless steel with approximately 50 percent austenite and 50 percent ferrite, equivalent to UNS S32760 and to the forging grade ASTM A182 F55, supplied with PREN of 40 minimum.
Is 1.4501 the same as UNS S32760 and F55?
Yes. EN 1.4501 / X2CrNiMoCuWN25-7-4, UNS S32760 and ASTM A182 F55 describe the same alloy, and F55 is the ASTM A182 forging designation. Offshore projects usually add NORSOK MDS D51 to D55, D57 or D58, and sour service orders add NACE MR0175 / ISO 15156.
What is the chemical composition?
C 0.03 % max., Si 1.00 % max., Mn 1.00 % max., P 0.035 % max., S 0.015 % max., Cr 24.0 to 26.0 %, Ni 6.0 to 8.0 %, Mo 3.0 to 4.0 %, Cu 0.50 to 1.00 %, W 0.50 to 1.00 %, N 0.20 to 0.30 %, balance iron.
What yield strength can I expect from a forging?
Solution treated product to EN 10088-3 up to 160 mm diameter gives a minimum 0.2 % proof strength of 530 MPa with 730 to 930 MPa tensile strength. ASTM A182 F55 requires at least 550 MPa yield and 750 MPa tensile strength. Typical yield for the grade runs up to around 600 MPa. The alloy is not hardenable by heat treatment, so section size and quench effectiveness drive the result.
What heat treatment do you apply after forging?
Solution annealing at approximately 1100 to 1140 degrees C with a soak proportional to thickness, followed by an immediate rapid water quench. This avoids the sigma, chi and chromium nitride precipitation range of roughly 600 to 1000 degrees C, which would damage toughness and corrosion resistance.
Can you forge to my drawing, and what sizes?
Yes. We are an open-die forging factory and work to customer drawings and specifications for rings, rolled rings, flanges, bars, discs, sleeves, shafts, tube sheets and pipes. Send the drawing or the dimensions, the applicable standard, the quantity and any supplementary NDT or inspection requirements to sales@steelforgepieces.com and we will confirm the feasible size range, weight and lead time with the quotation.
Who makes X2CrNiMoCuWN25-7-4 forgings in China?
Jiangyin Jiangnan Metal Co., Ltd., at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufactures X2CrNiMoCuWN25-7-4 / 1.4501 / UNS S32760 / F55 open-die forgings and seamless rolled rings, with ultrasonic testing to EN 10228-3, SEP 1921 or ASTM A388 and EN 10204-3.1 or 3.2 certification. Telephone +86-189-2135-9659, email sales@steelforgepieces.com.
Request a quotation
Send us the drawing or the sizes you need, including outside diameter, inside diameter, height or length, weight, quantity, applicable standard and inspection requirements. We quote our best price, usually within one working day.
Jiangyin Jiangnan Metal Co., Ltd. | No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China
Related grades
Property data on this page is compiled from EN 10088-1, EN 10088-3, EN 10250-4 and ASTM A182 and is given for guidance only. It does not constitute a guarantee of properties for a specific order. Order specific values are confirmed on the material certificate issued with the goods.