Super Duplex 2507 Stainless (UNS S32750)
25 Cr super duplex with a PREN above 40 — 116 ksi tensile and 80 ksi yield for the most aggressive seawater, sour and chloride bolting.
What Super Duplex 2507 is.
Super duplex 2507 raises chromium to 25 percent, molybdenum to 4 percent and nitrogen to 0.28 percent, pushing the pitting resistance equivalent number above 40. That is the threshold at which a stainless steel resists crevice corrosion in warm seawater, and it is why 2507 is the standard bolting for subsea manifolds, seawater lift pumps and hot sour production systems.
It is also the strongest of the common duplex grades, with an 80 ksi minimum yield and 116 ksi tensile in sizes to 2 inches under ASTM A1082. We machine 2507 from certified solution-annealed bar with full heat traceability.
Chemical composition.
| Element | Symbol | Min % | Max % |
|---|---|---|---|
| Carbon | C | — | 0.030 |
| Manganese | Mn | — | 1.20 |
| Phosphorus | P | — | 0.035 |
| Sulfur | S | — | 0.020 |
| Silicon | Si | — | 0.80 |
| Chromium | Cr | 24.0 | 26.0 |
| Nickel | Ni | 6.0 | 8.0 |
| Molybdenum | Mo | 3.0 | 5.0 |
| Nitrogen | N | 0.24 | 0.32 |
| Copper | Cu | — | 0.50 |
Values per ASTM A1082/A1082M-16(2021) Tables 1 and 4 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
Mechanical properties.
| Size | Tensile strength, min (ksi) | Yield strength, min (ksi) | Elongation, min (%) | Hardness, max |
|---|---|---|---|---|
| 2 in. and under | 116 | 80 | 15 | 33 HRC / 310 HBW |
| Over 2 in. | 110 | 75 | 15 | 33 HRC / 310 HBW |
Values per ASTM A1082/A1082M-16(2021) Tables 1 and 4 (verified against the specification). Confirm the edition called out on your purchase order with our estimating team.
Specifications that apply.
How Super Duplex 2507 ships from Houston.
- Full-thread studs and stud bolts
- Hex and heavy hex bolts
- Socket head cap screws
- Hex nuts in the same alloy
- Threaded rod
- Machined components from certified bar
Super Duplex 2507 fasteners we make.
Every item is manufactured to your drawing or standard in Super Duplex 2507, imperial or metric, with an EN 10204 3.1 certificate.
What is super duplex 2507?
2507 (UNS S32750) is the 25 Cr – 7 Ni – 4 Mo – 0.28 N member of the duplex family. Compared with 2205 it has more of everything that resists chloride attack, and its higher nitrogen keeps the austenite fraction stable after welding. The result is a stainless steel that survives in warm seawater, brines and wet sour gas where 2205 would pit, with a yield strength above many low-alloy bolting steels.
2507 or Zeron 100?
S32750 (2507) and S32760 (Zeron 100) are both 25 Cr super duplex grades and are often accepted interchangeably. S32760 adds copper and tungsten and carries a guaranteed PREN of 40 minimum in its chemistry; S32750 reaches the same range through higher nitrogen and molybdenum. A1082 rates 2507 stronger in small sizes, 116 ksi versus 109, while Zeron 100 has the higher elongation. Match the bolting to the flange grade, F53 for 2507 and F55 for Zeron 100, unless the specification allows either.
Limits
Keep super duplex below about 570 °F in service and above −50 °F where toughness is required. It must not be stress relieved or heat treated after machining, and it galls against itself, so specify an anti-seize or a dissimilar nut.
Testing, certification and marking
- Tensile and hardness tested per lot on the finished product
- Grade or alloy marking 32750 (A1082 Table 5) and manufacturer's identification on every piece
- EN 10204 3.1 material test report with heat number and chemistry; 3.2 witness available
Recent Super Duplex 2507 jobs.
Super Duplex Zeron 100 (UNS S32760, F55)
The copper-tungsten super duplex with a guaranteed PREN of 40 — the F55 bolting grade for North Sea, Gulf of Mexico and West African offshore projects.
ASTM A1082 bolting · ASTM A276 / A479 bar · ASTM A182 F51 / F60Duplex 2205 Stainless (UNS S31803 / S32205)
Twice the yield strength of 316 with far better chloride stress-corrosion resistance — the standard duplex for offshore, seawater and sour-service bolting.
ASTM B637 bar · AMS 5662 / 5663 · API 6A CRAInconel 718 (UNS N07718)
The premier high-strength nickel superalloy — 185 ksi tensile and 150 ksi yield from cryogenic temperatures to 1200 °F, with corrosion and sour-gas resistance to match.