Super Duplex 2507
UNS S32750 · Duplex stainless steel · Product-specific technical reference.
Super Duplex 2507 (S32750) is included here as a material reference. Ferrite/austenite give high proof strength and improved chloride SCC resistance compared with common 304L/316L in comparable conditions. SCC immunity, seawater suitability or a minimum PREN cannot be inferred from a family label.
Scope: Numerical limits below apply only to the named source, product form and condition. They are not measured results, design allowable stresses or guarantees for every product with this UNS. Acceptance follows the purchase order and applicable design/product standards.
1. Selected Chemical Requirements
Basis: ASTM A789/A789M-24, Table 1 (tube reference). Values are mass %. This selected-element table does not replace the complete source table and footnotes.
| Element | Requirement, mass % |
|---|---|
| C | ≤0.030 |
| Mn | ≤1.20 |
| P | ≤0.035 |
| S | ≤0.020 |
| Si | ≤0.80 |
| Cr | 24.0-26.0 |
| Ni | 6.0-8.0 |
| Mo | 3.0-5.0 |
| N | 0.24-0.32 |
| Cu | ≤0.50 |
A789 Table 1 note C additionally requires Cr + 3.3Mo + 16N ≥41.
2. Mechanical Requirements and Delivery Condition
Basis: ASTM A789/A789M-24, Table 4. Published room-temperature minima. The source MPa and ksi values are shown separately; do not combine unit systems when assessing an order.
| Product / condition / size | Tensile, MPa (ksi) | 0.2% proof / yield, MPa (ksi) | Elongation, % |
|---|---|---|---|
| Solution-treated tube | ≥ 800 (116) | ≥ 550 (80) | ≥ 15 |
Tube requirements; do not transfer automatically to A790 pipe. Table 4 specimen/small-size notes apply, including exclusions for very small OD or thin walls. Delivery follows Table 2 and the order.
3. Designation References
UNS S32750 is the material identifier used here. Cross-system names below are comparison candidates only. EN, JIS and GB/T grades can differ in chemistry, form, condition and testing; substitution requires a technical comparison and project-required approval.
| UNS | EN / DIN | EN name | JIS | GB / ISC |
|---|---|---|---|---|
| S32750 | 1.4410 | X2CrNiMoN25-7-4 | SUS327L1 | 022Cr25Ni7Mo4N |
These are recorded designation references, not a certification of equivalence. A dash means no confirmed entry is supplied. A common UNS number or commercial name does not establish branded origin.
4. Fabrication and Service Considerations
Ferrite/austenite give high proof strength and improved chloride SCC resistance compared with common 304L/316L in comparable conditions. SCC immunity, seawater suitability or a minimum PREN cannot be inferred from a family label.
Specify solution treatment/cooling under the actual product standard and control phase balance and detrimental precipitates through qualified processing and welding. Higher strength does not automatically permit a thinner wall. Check toughness and thermal exposure rather than imposing one universal temperature limit. For H₂S oil/gas duties, assess applicable ISO 15156-3 / NACE MR0175 material, weld and environmental requirements; PREN or hardness alone is insufficient. Calculate PREN from certified composition using the required formula and any product-standard combined-element requirement.
5. Product Standards and Ordering Basis
A789/A789M covers specified seamless/welded duplex tubing; A790/A790M covers specified seamless/welded duplex pipe. Confirm individual grade coverage and state seamless explicitly when required. A928/A928M is electric-fusion-welded pipe with filler metal, not seamless pipe. Tube and pipe properties can differ.
State grade/UNS, form, route, specification/edition, OD/wall/length, condition, examination and documents. ASME SA/SB acceptance and design-code permission require separate checks. EN 10204 type 3.1 is an inspection document, not independent product approval. Chemical and mechanical tests can use different heat/lot sampling bases.
6. Typical Applications
Qualified chloride-bearing chemical/water duties after pitting, crevice and SCC assessment.
These are examples, not a service-envelope approval. Confirm medium, concentration, temperature, pressure, flow/stagnation, deposits, crevices, stress and fabrication condition.
7. Product Enquiries and Related Pages
Forms, sizes, availability and certification are confirmed in the written quotation. Send an enquiry with the actual specification and service requirements.
Reference review: 30 October 2026. Editions identify the sources used; they do not assert that all named editions remain active or that alternative standards have identical requirements.