Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175 / ISO 15156-2
- NORSOK M-650 Qualified
- API 6A Certified
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Super Duplex Stainless Steel 2507 (UNS S32750 / Werkstoff 1.4410)
Super Duplex 2507 (also written 2507, SAF 2507, UR 52N+, Avesta 2507, UNS S32750, Werkstoff 1.4410, X2CrNiMoN25-7-4) is a nitrogen-enhanced super duplex stainless steel. Nominal composition is 25 Cr, 7 Ni, 3.5 to 4 Mo, 0.24 to 0.32 N, with no intentional copper and no intentional tungsten. PREN, calculated as Cr + 3.3 times Mo + 16 times N, sits at 41 or higher, qualifying the alloy as super duplex per NORSOK M-630. The microstructure is a balanced 50 to 50 mix of austenite and ferrite, achieved by solution annealing at 1040 to 1100 degrees Celsius and rapid water quench. The alloy is covered by ASTM A479 (bar), ASTM A789 (tube), ASTM A790 (pipe), ASTM A815 (fittings), ASTM A276 (shapes), ASTM A182 grade F53 (forgings and flanges), EN 10088-3, NORSOK M-630 and M-650, NACE MR0175 / ISO 15156, API 6A and API 17D.
Super Duplex 2507 is supplied by TorqBolt as fasteners, bar, round bar, plate, sheet, pipe, tube, fittings, flanges, forgings, and welding wire. Strength comes from the duplex microstructure itself: yield 550 MPa minimum, tensile 800 to 1000 MPa, with elongation above 25 percent and hardness no greater than 28 HRC for sour-service compliance per NACE MR0175.
Super Duplex 2507 Characteristics and Key Properties
Super Duplex 2507 is engineered for the most aggressive chloride environments where standard 2205 duplex and 6 percent molybdenum austenitics are insufficient and where the cost of nickel-base alloys cannot be justified. The combination of high chromium, controlled nickel, molybdenum, and nitrogen produces a PREN above 40 and a critical pitting temperature above 50 degrees Celsius per ASTM G48 Method E. Critical crevice temperature per ASTM G48 Method F sits at or above 35 degrees Celsius. The alloy retains tensile strength above 700 MPa at service temperatures up to about 250 degrees Celsius and is qualified for sour-service applications per NACE MR0175 and ISO 15156-3 with hardness restricted to 28 HRC maximum.
Super Duplex 2507 Mill Trademarks (SAF 2507, UR 52N+, Avesta 2507)
Three mill trademarks dominate global Super Duplex 2507 production. All three meet identical UNS S32750 chemistry and mechanical-property requirements; the choice of trademark is driven by mill availability, product form, and customer specification.
| Trademark | Mill | Designation | Common Forms |
|---|---|---|---|
| SAF 2507 | Sandvik (original developer) | UNS S32750 / 1.4410 | Tube, pipe, bar |
| UR 52N+ | Industeel ArcelorMittal | UNS S32750 / 1.4410 | Heavy plate, forging billet, large bar |
| Avesta 2507 | Outokumpu | UNS S32750 / 1.4410 | Plate, welded products |
Super Duplex 2507 Chemical Composition (UNS S32750 Element Ranges)
Super Duplex 2507 chemistry per ASTM A479, ASTM A182 grade F53, and EN 10088-3 (1.4410). Full element-by-element ranges are also detailed on the dedicated Super Duplex 2507 chemical composition page.
| Element | ASTM A479 / A182 F53 | EN 10088-3 (1.4410) | Typical Mill Heat |
|---|---|---|---|
| Carbon (C), max. | 0.030 | 0.030 | 0.020 |
| Manganese (Mn), max. | 1.20 | 1.20 | 0.80 |
| Phosphorus (P), max. | 0.035 | 0.035 | 0.025 |
| Sulfur (S), max. | 0.020 | 0.015 | 0.001 |
| Silicon (Si), max. | 0.80 | 1.00 | 0.40 |
| Chromium (Cr) | 24.0 to 26.0 | 24.0 to 26.0 | 25.0 |
| Nickel (Ni) | 6.0 to 8.0 | 6.0 to 8.0 | 7.0 |
| Molybdenum (Mo) | 3.0 to 5.0 | 3.0 to 5.0 | 3.8 |
| Nitrogen (N) | 0.24 to 0.32 | 0.24 to 0.32 | 0.28 |
| Copper (Cu) | No intentional addition (key distinguisher from S32760 Zeron 100 and S32550 Ferralium 255) | ||
| Tungsten (W) | No intentional addition (key distinguisher from S32760 Zeron 100) | ||
| PREN | 41 to 43 typical (Cr + 3.3 times Mo + 16 times N) | ||
Super Duplex 2507 Mechanical Properties (Yield, Tensile, Hardness)
Mechanical requirements per ASTM A479 and NORSOK M-630 for solution-annealed Super Duplex 2507. There is no aging or precipitation hardening step. Strength comes from the duplex microstructure itself.
| Property | Minimum | Typical | Test Standard |
|---|---|---|---|
| Yield strength (0.2 percent offset) | 550 MPa (80 ksi) | 620 to 720 MPa | ASTM A370 |
| Tensile strength | 795 MPa (115 ksi) | 800 to 1000 MPa | ASTM A370 |
| Elongation in 50 mm | 15 percent | 25 to 35 percent | ASTM A370 |
| Hardness (sour-service limit) | 28 HRC max | 25 to 28 HRC | ASTM E18 / NACE MR0175 |
| Charpy V-notch at minus 46 degrees Celsius | 45 J min | 60 to 100 J | NORSOK M-630, ASTM E23 |
| Critical pitting temperature (CPT) | 50 degrees Celsius | 55 to 70 degrees Celsius | ASTM G48 Method E |
| Critical crevice temperature (CCT) | 35 degrees Celsius | 40 to 50 degrees Celsius | ASTM G48 Method F |
| Ferrite content (base metal) | 35 to 55 percent | 45 to 50 percent | NORSOK M-630, ASTM E562 |
Super Duplex 2507 Heat Treatment (Solution Anneal Only)
Solution annealing at 1040 to 1100 degrees Celsius followed by rapid water quench. There is no precipitation hardening, no aging, no temper. The water quench must drive the material rapidly through the 600 to 1000 degrees Celsius band to avoid sigma-phase formation, which would cut Charpy toughness by 80 percent or more and compromise pitting resistance. See the dedicated heat treatment page and sigma-phase embrittlement reference for full TTT data and acceptance criteria.
Super Duplex 2507 Welding (ER2594 / ER2553)
Recommended fillers per AWS A5.9: ER2594 for overmatching service (slightly higher PREN than the base metal) and ER2553 for matching service. Both are nitrogen-enhanced. Heat input should remain between about 0.5 and 2.5 kJ per millimetre. Interpass temperature must stay below 150 degrees Celsius. Argon plus 2 to 5 percent nitrogen shielding is preferred for GTAW. Post-weld solution anneal at 1050 degrees Celsius and water quench is recommended for safety-critical applications. Full procedure detail is on the welding and welding filler pages.
Super Duplex 2507 ASTM, EN, NORSOK, NACE, API Specifications
The international specifications relevant to Super Duplex 2507 supply, qualification, and inspection.
| Standard | Scope | 2507 Designation |
|---|---|---|
| ASTM A479 | Stainless steel bars and shapes for boiler and pressure vessel use | UNS S32750 |
| ASTM A789 | Seamless and welded ferritic / austenitic stainless steel tube for general service | UNS S32750 |
| ASTM A790 | Seamless and welded ferritic / austenitic stainless steel pipe | UNS S32750 |
| ASTM A815 | Wrought ferritic, ferritic / austenitic, and martensitic stainless steel piping fittings | WP-S32750 |
| ASTM A182 F53 | Forgings, flanges, and forged fittings (CRITICAL: F53 is S32750. F55 is S32760, a different alloy) | Grade F53 |
| EN 10088-3 | Semi-finished products, bars, rods, wire, sections of stainless steel | 1.4410 / X2CrNiMoN25-7-4 |
| NORSOK M-630 | Material data sheet for super duplex stainless steel (Norwegian Continental Shelf) | MDS D55, D57 |
| NORSOK M-650 | Manufacturer qualification (QTR) for super duplex stainless steel | QTR required |
| NACE MR0175 | Petroleum and natural gas industries: materials for use in H2S-containing environments | 28 HRC max |
| API 6A | Wellhead and christmas tree equipment (PSL 3, 3G) | PSL 3 / 3G |
| API 17D | Subsea wellhead and tree equipment | Material class HH |
Super Duplex 2507 vs Zeron 100 vs Ferralium 255 vs Duplex 2205
All four alloys are duplex stainless steels but they are not interchangeable. The defining differences are copper and tungsten content, PREN, and forging spec.
| Alloy | UNS | Cu | W | PREN | Forging Spec |
|---|---|---|---|---|---|
| Super Duplex 2507 | S32750 | None | None | 41 to 43 | ASTM A182 F53 |
| Zeron 100 | S32760 | 0.5 to 1.0 | 0.5 to 1.0 | 41 to 44 | ASTM A182 F55 |
| Ferralium 255 | S32550 | 1.5 to 2.5 | None | 38 to 42 | ASTM A182 F61 |
| Duplex 2205 | S31803 / S32205 | None | None | 34 to 38 | ASTM A182 F51 |
Dedicated comparison pages: 2507 vs Zeron 100, 2507 vs Ferralium 255, 2507 vs Duplex 2205, 2507 vs Inconel 625.
Super Duplex 2507 Applications by Industry
Super Duplex 2507 dominates buyer specifications in four zones: seawater service, oil and gas (especially sour service), desalination, and chemical processing. The alloy is over-specified for fresh-water and benign service, and under-specified for the hottest most aggressive halide environments where nickel-base alloys remain the only safe choice.
- Seawater service at velocities up to about 6 metres per second, full-strength chloride exposure. Critical pitting temperature above 50 degrees Celsius per ASTM G48 Method E.
- Oil and gas downhole, surface, and subsea per NACE MR0175 sour-service compliance with hardness restricted to 28 HRC maximum.
- Desalination plants (MSF, MED, RO) for high-pressure brine piping and tubing.
- Chemical processing in dilute hydrochloric, sulfuric, hydrofluoric service.
- Marine and offshore topside, splash zone, subsea manifold, christmas tree.
- Pulp and paper bleach plants and chlorine dioxide service.
- Flue gas desulfurization (FGD) wet absorber, quencher, outlet duct.
- Sour service per NACE MR0175 and ISO 15156-3 with H2S partial pressure and chloride limits per zone.
Super Duplex 2507 Forms and Fasteners
TorqBolt holds Super Duplex 2507 stock at the Mumbai warehouse across the form and fastener range. India domestic delivery in 3 to 7 working days; export shipments through Mumbai port (JNPT) with full mill TC, packing list, and project-specific documentation.
| Form Category | Products |
|---|---|
| Bar and rod | Round bar, bar stock, hex bar, flat bar, square bar, forged bar, hollow bar, cold finished bar |
| Sheet, plate, tube, pipe | Sheet, plate, tube, pipe, welded pipe, wire |
| Fittings, flanges, forgings | Buttweld fittings, flanges, forgings |
| Fasteners | Bolts, hex bolts, heavy hex bolts, stud bolts, eye bolts, U-bolts, nuts, hex nuts, heavy hex nuts, lock nuts, washers, flat washers, lock washers, SHCS, screws, threaded rod |
Super Duplex 2507 Frequently Asked Questions
What is the PREN of Super Duplex 2507?
Approximately 41 to 43, calculated using the formula Cr + 3.3 times Mo + 16 times N. A typical mill heat with 25 percent chromium, 3.8 percent molybdenum, and 0.28 percent nitrogen yields PREN about 42. NORSOK M-630 requires PREN of 40 or above for super duplex classification.
Is Super Duplex 2507 the same as Zeron 100?
No. Both are super duplex stainless steels but Zeron 100 (UNS S32760) contains nominal 0.7 percent each of copper and tungsten. Super Duplex 2507 (UNS S32750) contains neither. The forging spec for 2507 is ASTM A182 F53; for Zeron 100 it is F55. The two are not drop-in substitutes when a project specification names one or the other by UNS number.
Which ASTM standards cover Super Duplex 2507?
A479 covers bar and shapes. A789 covers seamless and welded tube. A790 covers seamless and welded pipe. A815 covers wrought pipe fittings (designation WP-S32750). A276 covers stainless bar shapes. A182 grade F53 covers forgings, flanges, and forged fittings. International standards include EN 10088-3, NORSOK M-630, NACE MR0175, ISO 15156-3, API 6A, and API 17D.
What is the heat treatment of Super Duplex 2507?
Solution annealing at 1040 to 1100 degrees Celsius followed by rapid water quench. There is no precipitation hardening, no aging, no temper. The water quench must drive the material rapidly through the 600 to 1000 degrees Celsius band to avoid sigma-phase formation, which would cut Charpy toughness by 80 percent or more and compromise pitting resistance.
Is Super Duplex 2507 acceptable for sour service?
Yes, qualified per NACE MR0175 and ISO 15156-3 with hardness at 28 HRC maximum and ferrite content within 35 to 65 percent. Specific H2S partial pressure and chloride limits depend on the application zone classification. TorqBolt supplies 2507 fasteners and forgings with NACE compliance certification on request.
Why does Super Duplex 2507 have no copper or tungsten?
The defining chemistry of UNS S32750 is 25Cr-7Ni-3.5Mo-0.3N with no intentional copper or tungsten addition. Adding either changes the alloy. Zeron 100 (S32760) adds about 0.7 percent each. Ferralium 255 (S32550) adds copper. Mixing these chemistries on a 2507 page is incorrect and creates a chimeric specification that does not exist in any mill datasheet or ASTM standard.
Which welding filler is correct for Super Duplex 2507?
ER2594 (overmatching, slightly higher PREN than the base) is the most common choice per AWS A5.9. ER2553 (matching) is also acceptable for less aggressive service. Both are nitrogen-enhanced fillers.
In which forms is Super Duplex 2507 supplied?
TorqBolt manufactures Super Duplex 2507 in fasteners, bar, round bar, wire, sheet, plate, tubes, pipe, fittings, flanges and forgings.
What is Super Duplex 2507 used for?
Super Duplex 2507 is used in seawater service, oil and gas downhole and surface, desalination plants, marine and subsea hardware, chemical processing, pulp and paper bleach plants, and flue gas desulfurization. Service temperature range is approximately minus 50 degrees Celsius to 250 degrees Celsius continuous; sigma-phase risk above 300 degrees Celsius limits long-term high-temperature service.
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