Duplex & super duplex / UNS S32750
Super duplex 2507 raises chromium, molybdenum and nitrogen to give a pitting resistance equivalent (PREN) above 40, for seawater and other high-chloride service where 2205 is not enough.
- UNS S32750
- W.Nr. 1.4410
- Spec ASTM A240
- Density 7.8 g/cm³
Also known as / equivalents
| System | Designation |
|---|---|
| UNS | S32750 |
| W.Nr. | 1.4410 |
| EN | X2CrNiMoN25-7-4 |
| Also known as | 2507, F53, S32750, 1.4410, SAF 2507 |
Chemical composition
| Element | Min % | Max % |
|---|---|---|
| C | — | 0.030 |
| Mn | — | 1.20 |
| P | — | 0.035 |
| S | — | 0.020 |
| Si | — | 0.80 |
| Cr | 24.0 | 26.0 |
| Ni | 6.0 | 8.0 |
| Mo | 3.0 | 5.0 |
| Cu | — | 0.50 |
| N | 0.24 | 0.32 |
| Fe | Bal. | — |
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength (min) | 795 MPa (115.3 ksi) |
| Yield strength, 0.2% offset (min) | 550 MPa (79.8 ksi) |
| Elongation in 50 mm (min) | 15 % |
| Hardness | 310 HB max |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.8 g/cm³ | 0.282 lb/in³ |
| Magnetic response | Magnetic (ferritic-austenitic) | — |
Available forms & specifications
| Form | Specification | Size range |
|---|---|---|
| Sheets, plates & coils | ASTM A240 / ASME SA240 | 0.3 mm – 6 mm |
| Seamless & welded pipe | ASTM A790 / A928 | 1/8" – 24" NB |
| Tubes | ASTM A789 | 1/8" – 24" NB |
| Bars & rods | ASTM A276, A479 | 3 mm – 500 mm |
| Flanges & forgings | ASTM A182 / ASME SA182 (F51, F53, F55, F60, F61, F44) | 1/2" – 48" NB (larger on request) |
| Buttweld fittings | ASTM A815 | 1/2" – 48" NB |
Corrosion & temperature resistance
Duplex grades combine high strength with resistance to chloride pitting, crevice corrosion and stress-corrosion cracking; super duplex grades (PREN ≥ 40) are used for seawater and aggressive brines. Service is normally limited to about 250–300 °C because of embrittlement at higher temperatures.
Applications
Super Duplex 2507: Seawater systems, desalination, subsea. Offshore and subsea piping, desalination, chemical tankers, pulp bleaching, heat exchangers and pressure vessels where weight saving matters.
Super Duplex 2507 vs Duplex 2205
| Super Duplex 2507 | Duplex 2205 | |
|---|---|---|
| UNS | S32750 | S31803 / S32205 |
| Key property | PREN > 40, seawater grade | 2× strength of 316L, chloride-SCC resistant |
| Typical use | Seawater systems, desalination, subsea | Offshore piping, heat exchangers, tanks |
| Cr (wt %) | 24.0–26.0 | 21.0–23.0 |
| Ni (wt %) | 6.0–8.0 | 4.5–6.5 |
| Mo (wt %) | 3.0–5.0 | 2.5–3.5 |
| C (wt %) | ≤ 0.030 | ≤ 0.030 |
| Tensile / yield (min, MPa) | 795 / 550 | 620 / 450 |
Frequently asked questions
What is the UNS number of Super Duplex 2507?
Super Duplex 2507 is designated UNS S32750 (W.Nr. 1.4410, EN X2CrNiMoN25-7-4).
What is Super Duplex 2507 used for?
PREN > 40, seawater grade. Typical uses: seawater systems, desalination, subsea.
Is Super Duplex 2507 magnetic?
Magnetic (ferritic-austenitic).
In which forms can I buy Super Duplex 2507 from Rajkamal Metals?
Coils & Strips, Sheets & Plates, Pipes & Tubes, Round Bars & Rods, Structural Sections, Flanges, Buttweld Fittings, Socket Weld & Threaded Fittings, Fasteners, Ferrule / Instrumentation Fittings, Dish Ends, Custom Orders. Sizes as per standard; other sizes on request.
Do you supply a Mill Test Certificate with Super Duplex 2507?
Yes. Actual values are given in the Mill Test Certificate (EN 10204 3.1) supplied with each order.
What is the difference between Super Duplex 2507 and Duplex 2205?
Super Duplex 2507: pren > 40, seawater grade. Duplex 2205: 2× strength of 316l, chloride-scc resistant. See the comparison table on this page.
Last updated: 30 October 2026. Grade names identify the supply range; designations are not engineering equivalents. Availability, make, origin and documentation are confirmed at quotation.
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