"When selecting stainless steel for seawater systems, offshore platforms, or desalination equipment, the material code is more than a grade number. It determines which material specification, mechanical properties, corrosion resistance requirements, and inspection documents must be verified before purchase."
The primary material code for Super Duplex 2507 is UNS S32750, while its European material number is EN 1.4410 and its European steel name is X2CrNiMoN25-7-4. It is a high-alloy duplex stainless steel designed for demanding chloride-containing environments, combining high mechanical strength with excellent resistance to pitting corrosion, crevice corrosion, and chloride stress corrosion cracking.
However, UNS S32750 alone is not a complete purchasing specification. Buyers must also identify the product form, applicable ASTM or EN standard, dimensions, heat-treatment condition, testing requirements, and certification requirements. For example, Super Duplex 2507 seamless and welded pipes may be specified under ASTM A790, while forged flanges commonly require ASTM A182 Grade F53.
What is Super Duplex Stainless Steel 2507?
Super Duplex Stainless Steel 2507 is a highly alloyed stainless steel characterized by a dual-phase (duplex) microstructure consisting of both ferrite and austenite. Its chemical composition typically includes approximately 25% chromium, 7% nickel, and 4% molybdenum, along with a controlled addition of nitrogen.
Across various product forms, this material exhibits significantly higher strength than conventional austenitic stainless steels, such as 304L and 316L. However, it is not entirely corrosion-resistant in all environments. Its performance in practical applications depends on a range of factors, including chloride concentration, temperature, pH level, crevice geometry, applied stress, surface condition, and the quality of fabrication.
What Is the Material Code for Super Duplex 2507?
These designations identify the same general alloy family, but they do not all serve the same purpose. UNS S32750 identifies the alloy, EN 1.4410 identifies its European material number, and ASTM A182 F53 identifies a grade within a particular product specification for forgings and related pressure components.
| Identification system | Material code or designation |
|---|---|
| UNS | S32750 |
| EN / Werkstoffnummer | 1.4410 |
| EN steel name | X2CrNiMoN25-7-4 |
| Common alloy name | Super Duplex 2507 |
| Common short designation | 2507 |
| ASTM forged flange grade | A182 F53 |
| SAF 2507 | Manufacturer-specific trade name |
Important purchasing note: Always specify both the grade and the governing product standard. Writing only "2507 stainless steel" may leave the supplier unclear about the required manufacturing route, dimensional tolerances, testing, and acceptance criteria.
What Are the ASTM Standards for Super Duplex 2507?
Super Duplex 2507 is supplied in different product forms, and each form may be governed by a different standard.
| Product form | Common ASTM standard | Typical product application |
|---|---|---|
| Plate, sheet, and strip | ASTM A240/A240M | Pressure equipment, tanks, structural components |
| Bars and shapes | ASTM A276/A276M; ASTM A479/A479M | Machined parts, shafts, industrial components, pressure equipment |
| Seamless and welded pipe | ASTM A790/A790M | Process piping, seawater piping, chemical plants |
| Seamless and welded tube | ASTM A789/A789M | Heat exchangers and other tubular equipment |
| Forgings and flanges | ASTM A182/A182M, Grade F53 | Pressure flanges, forged fittings, valves, and components |
| Butt-welding fittings | ASTM A815/A815M, applicable WP-S32750 designation | Elbows, tees, reducers, and other piping fittings |
Note: The applicable edition, grade designation, product scope, and acceptance requirements must be confirmed against the purchase order and project specification.
For example, an offshore piping project may require UNS S32750 pipe conforming to ASTM A790, while a flange connected to that piping may require ASTM A182 Grade F53. Both components use the Super Duplex 2507 alloy family, but their product standards are different.
Chemical Composition (wt.%)
| Element | Min | Max |
| Carbon (C) | – | 0.030 |
| Chromium (Cr) | 24.0 | 26.0 |
| Nickel (Ni) | 6.0 | 8.0 |
| Molybdenum (Mo) | 3.0 | 5.0 |
| Nitrogen (N) | 0.24 | 0.32 |
| Manganese (Mn) | – | 1.20 |
| Silicon (Si) | – | 0.80 |
| Copper (Cu) | – | 0.50 |
| Phosphorus (P) | – | 0.035 |
| Sulfur (S) | – | 0.020 |
| Iron (Fe) | Balance | – |
Mechanical Properties (Solution Annealed)
| Property | Value |
| Tensile Strength (Rm) | ≥ 800 MPa / 116 ksi |
| 0.2% Proof Stress (Rp0.2) | ≥ 550 MPa / 80 ksi |
| 1.0% Proof Stress (Rp1.0) | ≥ 640 MPa / 93 ksi |
| Elongation (50 mm / 2 in) | ≥ 15% |
| Reduction of Area | ≥ 45% |
| Hardness | ≤ 310 HBW / ≤ 32 HRC |
| Impact Energy (RT) | ≥ 77 J (57 ft·lb) |
When should buyers choose 2507 instead of 2205 or 316L?
Super Duplex 2507 is worth evaluating when chloride exposure, localized corrosion risk, or mechanical loading exceeds the capabilities of more conventional grades. Duplex 2205 may provide a more economical solution for less aggressive conditions, while 316L may be suitable for many general industrial applications.
The correct choice should consider lifecycle cost, corrosion testing, operating conditions, inspection requirements, and the consequences of component failure.
UNS S32750 Stainless Steel Supplier
For buyers sourcing Super Duplex 2507 steel for industrial projects, GNEE provides comprehensive quotations. These quotes cover the required product forms, material specifications, dimensions, inspection requirements, and export documentation, subject to current stock availability and production capacity.
When submitting an inquiry, please specify the product type required for your project (e.g., pipes, plates, bars, flanges, or pipe fittings), along with the applicable standards and acceptance criteria.
For specific orders, GNEE can facilitate the following requirements:
Material Identification: Compliance with the UNS S32750 standard and relevant product specifications.
Technical Documentation: Provision of Mill Test Certificates (MTCs) and heat number traceability, in accordance with the terms of the purchase order.
Inspection Coordination: Execution of dimensional checks, Positive Material Identification (PMI), and other necessary testing as per the agreed-upon inspection plan.
Export Packaging: Protective wrapping, end protection, secure crating, and packaging compliant with international maritime shipping requirements.
FAQ
Q. Is UNS S32750 the same as EN 1.4410?
They are widely recognized designations for the same general Super Duplex 2507 alloy. However, the applicable product standard, chemical limits, mechanical requirements, and inspection criteria must still be checked before treating materials as interchangeable for a project.
Q. What is ASTM A182 F53?
ASTM A182 Grade F53 is a forged-material grade commonly used for Super Duplex 2507 flanges and other applicable pressure components. It is not the general product standard for every form of 2507 stainless steel.
Q. Is Super Duplex 2507 better than 316L stainless steel?
For many severe chloride-containing environments, 2507 offers higher strength and better resistance to localized corrosion than 316L. However, it generally costs more and requires appropriate fabrication controls. The best material depends on the actual operating environment and project requirements.
Q. What is the difference between Super Duplex 2507 and UNS S32760?
UNS S32750 and UNS S32760 are distinct super duplex stainless steel grades. They have different specified chemical-composition limits and should not be treated as identical merely because both are called super duplex. Verify the required UNS number on the purchase order and MTC.
Q. Does Super Duplex 2507 resist seawater corrosion?
It offers excellent resistance to many forms of chloride-related corrosion, making it suitable for numerous seawater applications. However, stagnant conditions, deposits, crevices, high temperatures, and specific seawater chemistry can still cause corrosion. Suitability must be evaluated for the actual service conditions.
Q. What information is needed to buy Super Duplex 2507?
At minimum, specify the UNS grade, product form, applicable standard, dimensions, quantity, delivery condition, certification, inspection requirements, and destination. For critical service, also provide the operating temperature, fluid composition, chloride concentration, design pressure, and relevant project code.