Duplex & super duplex / UNS S32550
Ferralium® 255 (UNS S32550, F61) is a copper-bearing super duplex stainless steel with high strength and good resistance to sulphuric acid, chlorides and erosion-corrosion. It is a separate grade, not an equivalent of 2507.
- UNS S32550
- W.Nr. 1.4507
- Spec ASTM A240
- Density 7.81 g/cm³
Also known as / equivalents
| System | Designation |
|---|---|
| UNS | S32550 |
| W.Nr. | 1.4507 |
| EN | X2CrNiMoCuN25-6-3 |
| Also known as | F61, S32550, 1.4507, Alloy 255 |
Chemical composition
| Element | Min % | Max % |
|---|---|---|
| C | — | 0.04 |
| Mn | — | 1.50 |
| P | — | 0.040 |
| S | — | 0.030 |
| Si | — | 1.00 |
| Cr | 24.0 | 27.0 |
| Ni | 4.5 | 6.5 |
| Mo | 2.9 | 3.9 |
| Cu | 1.50 | 2.50 |
| N | 0.10 | 0.25 |
| Fe | Bal. | — |
Mechanical properties
| Property | Value |
|---|---|
| Tensile strength (min) | 760 MPa (110.2 ksi) |
| Yield strength, 0.2% offset (min) | 550 MPa (79.8 ksi) |
| Elongation in 50 mm (min) | 15 % |
| Hardness | 302 HB max |
Physical properties
| Property | Metric | Imperial |
|---|---|---|
| Density | 7.81 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
Ferralium® 255: Pumps, valves, scrubbers, marine. Offshore and subsea piping, desalination, chemical tankers, pulp bleaching, heat exchangers and pressure vessels where weight saving matters.
Frequently asked questions
What is the UNS number of Ferralium® 255?
Ferralium® 255 is designated UNS S32550 (W.Nr. 1.4507, EN X2CrNiMoCuN25-6-3).
What is Ferralium® 255 used for?
Copper-bearing, acid & erosion resistant. Typical uses: pumps, valves, scrubbers, marine.
Is Ferralium® 255 magnetic?
Magnetic (ferritic-austenitic).
In which forms can I buy Ferralium® 255 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 Ferralium® 255?
Yes. Actual values are given in the Mill Test Certificate (EN 10204 3.1) supplied with each order.
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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