Super Duplex 2507: properties, composition, uses and standards
Super Duplex 2507 is a super duplex stainless steel, chosen for seawater and high-chloride service where strength also matters. UNS S32750, W.Nr 1.4410, PREN ≈ 42, density 7.8 g/cm³.
What is Super Duplex 2507?
Super Duplex 2507 is a super duplex stainless steel. Engineers choose it for seawater and high-chloride service where strength also matters. It is also known as UNS S32750, W.Nr 1.4410, F53, SAF 2507.
- UNS
- S32750
- W.Nr
- 1.4410
- EN
- X2CrNiMoN25-7-4
- Forging grade
- F53
- Trade names
- SAF 2507
- Density
- 7.8 g/cm³
- Melting range
- 1350 – 1400 °C
- Magnetic
- Magnetic (ferritic phase)
- PREN (approx.)
- ≈ 42
Chemical composition and what each element does
| Element | Weight % |
|---|---|
| Chromium | 24.0 – 26.0 |
| Nickel | 6.0 – 8.0 |
| Molybdenum | 3.0 – 5.0 |
| Nitrogen | 0.24 – 0.32 |
| Copper | 0.50 max |
| Carbon | 0.030 max |
| Manganese | 1.20 max |
| Silicon | 0.80 max |
| Phosphorus | 0.035 max |
| Sulphur | 0.020 max |
| Iron | Balance |
Per ASTM A240 for UNS S32750.
High chromium, molybdenum and nitrogen put PREN above 40 — the usual threshold for seawater service.
Yield strength around 550 MPa, more than twice 316L.
Excellent resistance to chloride stress-corrosion cracking.
Keep service below about 250 °C.
Super Duplex 2507 at a glance
See the Super Duplex 2507 product page for every form we supply and its standard.
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength | 795 MPa · 116 ksi |
| Yield strength 0.2% | 550 MPa · 80 ksi |
| Elongation | 15% |
| Hardness | 310 HB max |
Solution-annealed plate & sheet, minimum values. Values for pipe, bar and forgings differ slightly — see the product standard.
Where Super Duplex 2507 is used
- Offshore & subsea. Seawater injection, firewater and subsea piping. Industry →
- Desalination. High-pressure RO piping. Industry →
- Chemical. Chloride-laden process streams. Industry →
- Marine. Propeller shafts and pump parts. Industry →
Welding 2507
The matching filler is ER2594 (AWS A5.9). Tight heat-input control and ferrite checks on procedure qualification.
Keep heat input moderate and interpass temperature low, clean joints thoroughly, and pickle or passivate after welding where the service is corrosive.
Super Duplex 2507 compared with similar grades
| Grade | PREN | Choose it for |
|---|---|---|
| Super Duplex 2507 | ≈ 42 | Seawater and high-chloride service where strength also matters |
| Duplex 2205 | ≈ 35 | Strength with chloride resistance at a stainless-steel budget |
| Inconel 625 | ≈ 51 | Seawater, high strength and high temperature in one alloy |
| Hastelloy C276 | ≈ 68 | The most aggressive mixed acids, wet chlorine and hypochlorite |
Super Duplex 2507 standards by product
Buying Super Duplex 2507: what to specify
- The product standard and the UNS or designation — for example ASTM A240 UNS S32750.
- Size, thickness or schedule, and quantity in pieces and kg or metres.
- Heat-treatment condition where the standard offers a choice.
- Certificate: EN 10204 3.1 as standard, 3.2 if a third party must witness.
- NACE MR0175 / ISO 15156 compliance if the service contains H₂S.