Super Duplex S32750 / S32760 / S32550 Round Bars
Super duplex stainless steels are 25 % chromium ferritic-austenitic alloys with a PREN above 40, developed for the toughest offshore, sub-sea and chemical process environments. UNS S32750 (2507) and S32760 (with tungsten and copper) combine very high strength with resistance to pitting, crevice corrosion and stress corrosion cracking in hot seawater and sour hydrocarbons, while S32550 (Ferralium 255) offers exceptional erosion-corrosion resistance and high strength for pump and valve components.
Nexforge Alloys manufactures and stocks super duplex round bars in the solution annealed condition, with each heat tested for ferrite content, absence of intermetallic phases (ASTM A923 / A1084), impact toughness and ASTM G48 pitting resistance. Bars are supplied to ASTM A276 / A479 and can also be certified to NORSOK M-630 material data sheets.
Super Duplex S32750 (F53), S32760 (F55) and S32550 (F61) round bars from 6 mm to 350 mm diameter, solution annealed, PREN ≥ 40, with ASTM G48 and A923 test reports.
Super Duplex Round Bar Specification
| Parameter | Details |
|---|---|
| Alloy Designations | S32750 (2507, F53, 1.4410), S32760 (F55, Zeron 100, 1.4501), S32550 (F61, Ferralium 255, 1.4507) |
| Standards | ASTM A276, ASTM A479, ASME SA479, ASTM A182 F53 / F55 / F61, EN 10088-3, NORSOK M-630 MDS D55/D57 |
| Size Range | 6 mm to 350 mm diameter |
| Length | Random 3 to 6 metres, or cut to length |
| Condition | Solution annealed at 1050 - 1125 °C and water quenched |
| Surface Finish | Hot rolled pickled, peeled, centreless ground, bright, rough turned |
| Tolerance | h9 / h10 / h11 or as per drawing |
| Testing | Chemical, tensile, impact at -46 °C, hardness, ferrite count, ASTM A923 / A1084, ASTM G48, UT |
| Certification | EN 10204 3.1 mill test certificate; 3.2 on request |
Chemical Composition (% by weight)
| Grade (UNS) | C | Mn | Si | P | S | Cr | Ni | Mo | N | Cu | W | Fe |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Super Duplex S32750 | 0.030 max | 1.20 max | 0.80 max | 0.035 max | 0.020 max | 24.0 - 26.0 | 6.0 - 8.0 | 3.0 - 5.0 | 0.24 - 0.32 | 0.50 max | - | Balance |
| Super Duplex S32760 | 0.030 max | 1.00 max | 1.00 max | 0.030 max | 0.010 max | 24.0 - 26.0 | 6.0 - 8.0 | 3.0 - 4.0 | 0.20 - 0.30 | 0.50 - 1.00 | 0.50 - 1.00 | Balance |
| Super Duplex S32550 | 0.040 max | 1.50 max | 1.00 max | 0.040 max | 0.030 max | 24.0 - 27.0 | 4.5 - 6.5 | 2.9 - 3.9 | 0.10 - 0.25 | 1.50 - 2.50 | - | Balance |
Mechanical Properties
| Grade | Tensile Strength (min) | 0.2% Yield Strength (min) | Elongation (min) | Hardness (max) | PREN | Density |
|---|---|---|---|---|---|---|
| S32750 (F53) | 800 MPa (116 ksi) | 550 MPa (80 ksi) | 15 % | 310 HB / 32 HRC | ≥ 41 | 7.80 g/cm³ |
| S32760 (F55) | 750 MPa (109 ksi) | 550 MPa (80 ksi) | 25 % | 270 HB / 28 HRC | ≥ 40 | 7.80 g/cm³ |
| S32550 (F61) | 760 MPa (110 ksi) | 550 MPa (80 ksi) | 15 % | 302 HB / 32 HRC | ≥ 38 | 7.81 g/cm³ |
Values are minimum or typical figures as per the referenced standards and are for guidance only. Please refer to the mill test certificate supplied with the material for actual values.
Key Features
- PREN above 40 for resistance to pitting and crevice corrosion in hot seawater
- Yield strength of 550 MPa, more than double that of 316L
- Excellent resistance to chloride stress corrosion cracking and sulphide stress cracking (NACE MR0175)
- S32550 gives outstanding erosion-corrosion and cavitation resistance
Applications
- Sub-sea and topside oil and gas components, wellhead and manifold parts
- Pump shafts, impellers, valve stems and fasteners in seawater service
- Desalination plant high pressure pumps and piping
- FGD scrubbers and chemical process equipment with high chloride content
- Firewater systems, propeller shafts and marine hardware