ASTM A240 / ASME SA-240 UNS S32750 Super Duplex Plate – EN 1.4410
ASTM A240 UNS S32750 Super Duplex Stainless Steel Plate is a 25Cr super duplex grade designed for high strength and excellent resistance to pitting, crevice corrosion and chloride stress corrosion cracking.
UNS S32750 is commonly referred to as Super Duplex 2507 and is cross-referenced with EN 1.4410 / X2CrNiMoN25-7-4. It is widely used in offshore, subsea, desalination, chemical processing, pressure vessels and other severe chloride-containing environments.
For projects governed by applicable ASME Boiler and Pressure Vessel Code requirements, the material may be specified as ASME SA-240 UNS S32750, subject to the applicable Code edition and project specification.
ASME SA-240 UNS S32750 Specification
| Item | Specification |
|---|---|
| Product | Super Duplex Stainless Steel Plate / Sheet |
| ASTM Grade | ASTM A240 UNS S32750 |
| ASME Designation | SA-240 S32750, when applicable |
| Common Name | Super Duplex 2507 |
| EN Designation | 1.4410 / X2CrNiMoN25-7-4 |
| Microstructure | Austenitic-Ferritic Duplex |
| Delivery Condition | Solution Annealed |
| Product Form | Hot Rolled Plate / Cold Rolled Sheet |
| Surface | No.1 / 2D / 2B or project-specific finish |
| Dimensions | Custom sizes subject to mill availability |
| General Tolerances | ASTM A480/A480M where applicable |
| Certification | EN 10204 3.1 when specified |
| Optional Testing | PMI, Ferrite, ASTM A923, ASTM G48, UT, TPI when specified |
What Is UNS S32750 Super Duplex?
UNS S32750 is a high-alloy super duplex stainless steel containing approximately 25% chromium, 7% nickel and 4% molybdenum with controlled nitrogen.
Its duplex austenitic-ferritic microstructure provides:
- Very high mechanical strength
- Excellent chloride stress corrosion cracking resistance
- High resistance to pitting and crevice corrosion
- Good resistance to many aggressive process environments
- Good weldability when suitable procedures are used
Compared with standard Duplex 2205, S32750 provides higher alloy content, higher strength and greater localized corrosion resistance.
UNS S32750, EN 1.4410 and SAF® 2507
| Designation | System | Relationship |
|---|---|---|
| UNS S32750 | UNS / ASTM | Generic material designation |
| EN 1.4410 | EN | Common European cross-reference |
| X2CrNiMoN25-7-4 | EN | European grade name |
| SAF® 2507 | Proprietary trade name | Alleima trademark for its S32750 grade |
SAF® 2507 should not be used as a generic manufacturer designation for all UNS S32750 material.
For general product descriptions, UNS S32750 Super Duplex 2507 is the more appropriate terminology unless the material is specifically supplied as SAF® 2507.
Chemical Composition – UNS S32750
| Element | Requirement |
|---|---|
| Carbon, C | ≤ 0.030% |
| Manganese, Mn | ≤ 1.20% |
| Silicon, Si | ≤ 0.80% |
| Phosphorus, P | ≤ 0.035% |
| Sulfur, S | ≤ 0.020% |
| 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% |
| Iron, Fe | Balance |
Actual chemical composition should be verified against the Material Test Certificate (MTC) for the supplied heat.
Mechanical Properties
Typical minimum ASTM A240 requirements for S32750 plate include:
| Property | Minimum Requirement |
|---|---|
| Yield Strength | 550 MPa |
| Tensile Strength | 795 MPa |
| Elongation | 15% |
The high yield strength of S32750 is one of its main advantages compared with conventional austenitic stainless steels and standard duplex grades.
PREN and Corrosion Resistance
A commonly used formula for evaluating pitting resistance is:
PREN = %Cr + 3.3 × %Mo + 16 × %N
Because S32750 contains high levels of chromium, molybdenum and nitrogen, it is generally associated with high resistance to localized chloride corrosion.
However, PREN ≥40 should not automatically be described as a mandatory ASTM A240 requirement.
If a project specifies a minimum PREN, such as PREN ≥40, it should be stated in the purchase specification and verified using the actual heat chemistry.
S32750 is commonly selected for environments involving:
- Seawater
- High chloride concentration
- Offshore and subsea service
- Desalination
- Chemical processing
- Aggressive process fluids
Final material selection should still consider temperature, chloride concentration, crevice conditions and the complete operating environment.
ASTM A240, ASME SA-240 and ASTM A480
ASTM A240/A240M specifies material requirements for stainless steel plate, sheet and strip used for pressure vessels and general applications.
For ASME Code projects, SA-240 may be specified according to the applicable ASME BPVC requirements.
ASTM A480/A480M provides general requirements applicable to flat-rolled stainless steel products, including dimensional tolerances and other general manufacturing requirements.
The applicable thickness and flatness tolerances depend on:
- Product form
- Plate or sheet dimensions
- Manufacturing route
- Ordered specification
- Applicable standard edition
For this reason, ASTM A480 tolerance tables should be applied according to the actual ordered product rather than treated as one universal tolerance table.
Testing and Inspection
Standard material compliance should be separated from additional project testing.
Typical supply verification includes:
- Chemical composition
- Mechanical properties
- Dimensions
- Surface condition
- Material traceability
- MTC review
Additional project requirements may include:
- Positive Material Identification – PMI
- Ferrite measurement
- Ultrasonic Testing – UT
- Hardness testing
- ASTM A923 testing
- ASTM G48 corrosion testing
- EN 10204 3.1 / 3.2 certification
- Third-party inspection
ASTM A923 is specifically used to evaluate detrimental intermetallic phases in applicable duplex stainless steels.
These additional tests should be specified at RFQ stage and should not automatically be considered mandatory ASTM A240 requirements.
Sour Service and NACE Requirements
UNS S32750 should not automatically be described as universally NACE compliant.
For H₂S-containing environments, the RFQ should specify the applicable requirements, such as:
NACE MR0175 / ISO 15156
Suitability depends on the material condition, hardness, temperature, H₂S partial pressure, chloride concentration and actual service environment.
Applications
UNS S32750 Super Duplex Plate is commonly used for:
- Offshore platforms
- Subsea equipment
- Seawater systems
- Desalination plants
How to Order UNS S32750 Plate
A complete RFQ should normally include:
Standard + Grade + Thickness + Width + Length + Quantity + Surface + Certification + Additional Testing
Example:
PLATE, ASTM A240 UNS S32750, 10 × 1500 × 6000 MM, HOT ROLLED NO.1, SOLUTION ANNEALED, EN 10204 3.1, QTY: 10 PCS
For sheet:
SHEET, ASTM A240 UNS S32750, 6 × 1500 × 6000 MM, EN 10204 3.1, QTY: 8 PCS
If additional requirements apply, specify PMI, PREN, ASTM A923, ASTM G48, ferrite limits, UT or third-party inspection in the RFQ.
Frequently Asked Questions
What is UNS S32750?
UNS S32750 is a 25Cr super duplex stainless steel designed for high mechanical strength and high resistance to chloride-induced localized corrosion.
Is UNS S32750 the same as Super Duplex 2507?
Yes, Super Duplex 2507 is the commonly used generic description for UNS S32750.
Is UNS S32750 the same as SAF® 2507?
UNS S32750 is the generic UNS material designation. SAF® 2507 is a proprietary Alleima trademark for its S32750 material.
What is the EN equivalent of UNS S32750?
The commonly cross-referenced European designation is EN 1.4410 / X2CrNiMoN25-7-4.
Cross-standard compliance should still be confirmed against the applicable product specification and MTC.
Is PREN ≥40 mandatory for ASTM A240 S32750?
Not automatically. If a minimum PREN is required by the project, it should be explicitly stated in the purchase specification and verified from actual heat chemistry.
What is the difference between S32750 and Duplex 2205?
S32750 contains higher chromium, molybdenum and nitrogen than Duplex 2205 and generally provides higher strength and better resistance to localized chloride corrosion.
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UNS S32750 Super Duplex Plate Supplier & Exporter
We supply and export ASTM A240 / ASME SA-240 UNS S32750 Super Duplex Stainless Steel Plate for offshore, oil & gas, desalination, chemical, marine and pressure-equipment projects.
Hot-rolled plate, cold-rolled sheet, custom dimensions and project-specific requirements such as EN 10204 3.1 certification, PMI, ferrite measurement, ASTM A923, ASTM G48, UT and third-party inspection can be supported when specified and commercially available.
Send us your standard, grade, thickness, width, length, quantity and inspection requirements for technical review and quotation.
