Duplex and super duplex stainless steel
Stainless with half ferrite and half austenite: twice the strength of 316L and high resistance to pitting and stress corrosion cracking in chlorides.
Duplex and super duplex stainless steel: alloys supplied by Dustre
Forms: Bar, Plate, Pipe, Forging and flange, Fitting, Casting. Click an alloy to see standards by form, composition, properties and equivalents.
| Material | UNS | W.Nr. / EN | Forms |
|---|---|---|---|
| Duplex 2205 (F51 / S31803)Duplex · All standards by product form | S31803 | 1.4462 X2CrNiMoN22-5-3 | Bar, Plate, Pipe, Forging and flange, Fitting, Casting |
| Duplex S32205 / F60Duplex · All standards by product form | S32205 | 1.4462 X2CrNiMoN22-5-3 | Bar, Plate, Pipe, Forging and flange, Fitting, Casting |
| Ferralium 255 / F61Super duplex · 25Cr-6Ni-3.5Mo-2Cu-N super duplex stainless steel | S32550 | 1.4507 | Bar, Plate, Pipe, Forging and flange |
| 329 stainless steelDuplex · First-generation 25Cr-4Ni-1.5Mo duplex stainless steel | S32900 | 1.4460 | Bar, Plate, Pipe, Forging and flange |
| Super duplex 2507 / F53 / S32750Super duplex · All standards by product form | S32750 | 1.4410 X2CrNiMoN25-7-4 | Bar, Plate, Pipe, Forging and flange, Fitting, Casting |
| Super duplex Zeron 100 / F55 / S32760Super duplex · All standards by product form | S32760 | 1.4501 X2CrNiMoCuWN25-7-4 | Bar, Plate, Pipe, Forging and flange, Fitting, Casting |
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Which alloy resists each environment
Indicative summary from the corrosive media calculator, under typical conditions. For your medium, concentration and temperature, use the calculator.
| Material | Fresh water (200 ppm Cl⁻, 25 °C) | Seawater (20,000 ppm Cl⁻, 25 °C) | Sulfuric acid 20 %, 40 °C | Air at 800 °C |
|---|---|---|---|---|
| Duplex S32205 / F60 | very good | limited | very good | not recommended |
| Super duplex 2507 / F53 / S32750 | very good | very good | very good | not recommended |
About duplex and super duplex stainless steel
Duplex 2205 (UNS S32205/S31803, forgings F51 and F60) is the standard for seawater, brine, pulp and chloride-bearing chemicals, with PREN from 35 to 36. The super duplex grades 2507 (F53, S32750) and Zeron 100 (F55, S32760) have PREN above 40 and serve wells, wellheads and offshore pumps per NORSOK M-630 and NACE MR0175.
The service limit lies between −50 and 250 °C; above that the ferrite embrittles. Welding and heat treatment require phase control (35–65 % ferrite), which Dustre verifies in the laboratory.
See also
Frequently asked questions
Are F51 and F60 the same material?
Almost: both are duplex 2205. F60 (S32205) has tighter nitrogen and molybdenum ranges and a higher minimum PREN; it meets most F51 (S31803) orders, but not the other way around.
Can duplex go to 300 °C?
Not recommended above 250 °C in continuous service: the ferrite suffers 475 °C embrittlement and sigma phase precipitation. For high temperature use austenitic or Cr-Mo.