Long exposure threshold
Above 250 deg C / 480 deg F, prolonged exposure can change microstructure and reduce impact strength
Super duplex stainless steel / UNS S32750
Super Duplex UNS S32750 / 2507 Material Data for Severe Chloride Service
A controlled Super Duplex 2507 benchmark page for materials engineers specifying high-strength austenitic-ferritic stainless flanges and pipe fittings in chloride-rich offshore, seawater, desalination, and process environments. The page frames chemistry, mechanical-property references, ASTM product routes, temperature cautions, NACE review, IGC considerations, and substitution decisions through verified structured content.
Quick technical snapshot
Verified facts first, project assumptions second.
The snapshot is published only from controlled structured data. Anything that needs review stays out of the authoritative display.
Pressure-vessel caution
Published guidance identifies 250 deg C / 480 deg F as a maximum for certain pressure-vessel applications under named European/Nordic rules
Solution annealing
1050-1125 deg C / 1920-2060 deg F followed by rapid cooling in air or water
| Specification | Verified value | Unit |
|---|---|---|
| UNS | S32750 | - |
| ASTM specifications | ASTM A182, A815, A789/A790, A240, A479Confirm current project grade, class, product form, dimensions, and supplementary requirements before ordering. | - |
| Alloy family | 25Cr super duplex austenitic-ferritic stainless steel | - |
| Density | 7.8 | g/cm3 |
| General corrosion characteristics | Excellent chloride SCC resistance, pitting and crevice corrosion resistance, high general corrosion resistance, and erosion-corrosion performance | - |
| Temperature considerations | Prolonged exposure above 250 deg C / 480 deg F requires careful review because microstructural changes can reduce impact strength | - |
| Typical industries | Offshore, subsea, seawater cooling, desalination, petrochemical, chemical processing, pulp and paper | - |
Products and size range
Standard scope for a more complete RFQ.
Each material has its own controlled capability record, giving buyers standard dimensional context before final RFQ specification review.
Flanges
Standard dimensional coverage, pressure-class architecture, facing options, and bore review.
Butt-weld fittings
Standard NPS / DN architecture, fitting geometry, schedule or wall, and end preparation control.
Forged fittings
Socket-weld and threaded fitting architecture with class and end-connection review.
| Nominal size | DN | Product | Standard | RFQ review |
|---|---|---|---|---|
| 1/2" | DN 15 | Flange | ASME B16.5 | |
| 3/4" | DN 20 | Flange | ASME B16.5 | |
| 1" | DN 25 | Flange | ASME B16.5 | |
| 1-1/4" | DN 32 | Flange | ASME B16.5 | |
| 1-1/2" | DN 40 | Flange | ASME B16.5 | |
| 2" | DN 50 | Flange | ASME B16.5 | |
| 2-1/2" | DN 65 | Flange | ASME B16.5 | |
| 3" | DN 80 | Flange | ASME B16.5 | |
| 4" | DN 100 | Flange | ASME B16.5 | |
| 5" | DN 125 | Flange | ASME B16.5 | |
| 6" | DN 150 | Flange | ASME B16.5 | |
| 8" | DN 200 | Flange | ASME B16.5 | |
| 10" | DN 250 | Flange | ASME B16.5 | |
| 12" | DN 300 | Flange | ASME B16.5 | |
| 14" | DN 350 | Flange | ASME B16.5 | |
| 16" | DN 400 | Flange | ASME B16.5 | |
| 18" | DN 450 | Flange | ASME B16.5 | |
| 20" | DN 500 | Flange | ASME B16.5 | |
| 22" | DN 550 | Flange | ASME B16.5 | |
| 24" | DN 600 | Flange | ASME B16.5 |
| Nominal size | DN | Product | Standard | RFQ review |
|---|---|---|---|---|
| 1/2" | DN 15 | Butt-weld fitting | ASME B16.9 | |
| 3/4" | DN 20 | Butt-weld fitting | ASME B16.9 | |
| 1" | DN 25 | Butt-weld fitting | ASME B16.9 | |
| 1-1/4" | DN 32 | Butt-weld fitting | ASME B16.9 | |
| 1-1/2" | DN 40 | Butt-weld fitting | ASME B16.9 | |
| 2" | DN 50 | Butt-weld fitting | ASME B16.9 | |
| 2-1/2" | DN 65 | Butt-weld fitting | ASME B16.9 | |
| 3" | DN 80 | Butt-weld fitting | ASME B16.9 | |
| 4" | DN 100 | Butt-weld fitting | ASME B16.9 | |
| 5" | DN 125 | Butt-weld fitting | ASME B16.9 | |
| 6" | DN 150 | Butt-weld fitting | ASME B16.9 | |
| 8" | DN 200 | Butt-weld fitting | ASME B16.9 | |
| 10" | DN 250 | Butt-weld fitting | ASME B16.9 | |
| 12" | DN 300 | Butt-weld fitting | ASME B16.9 | |
| 14" | DN 350 | Butt-weld fitting | ASME B16.9 | |
| 16" | DN 400 | Butt-weld fitting | ASME B16.9 | |
| 18" | DN 450 | Butt-weld fitting | ASME B16.9 | |
| 20" | DN 500 | Butt-weld fitting | ASME B16.9 | |
| 22" | DN 550 | Butt-weld fitting | ASME B16.9 | |
| 24" | DN 600 | Butt-weld fitting | ASME B16.9 | |
| 26" | DN 650 | Butt-weld fitting | ASME B16.9 | |
| 28" | DN 700 | Butt-weld fitting | ASME B16.9 | |
| 30" | DN 750 | Butt-weld fitting | ASME B16.9 | |
| 32" | DN 800 | Butt-weld fitting | ASME B16.9 | |
| 34" | DN 850 | Butt-weld fitting | ASME B16.9 | |
| 36" | DN 900 | Butt-weld fitting | ASME B16.9 | |
| 38" | DN 950 | Butt-weld fitting | ASME B16.9 | |
| 40" | DN 1000 | Butt-weld fitting | ASME B16.9 | |
| 42" | DN 1050 | Butt-weld fitting | ASME B16.9 | |
| 44" | DN 1100 | Butt-weld fitting | ASME B16.9 | |
| 46" | DN 1150 | Butt-weld fitting | ASME B16.9 | |
| 48" | DN 1200 | Butt-weld fitting | ASME B16.9 |
Material overview
Super Duplex 2507 material data for engineering review.
The narrative supports specification review without replacing the engineer's design basis, corrosion review, or purchase standard.
Super Duplex UNS S32750 / 2507 is a high-strength grade commonly considered for chloride service when standard austenitic stainless grades may be exposed to pitting, crevice corrosion, chloride stress corrosion cracking, or high mechanical load.
The alloy's value is not only chemical resistance. The high proof strength changes flange, fitting, support, and fabrication discussions, so RFQs should include product form, pressure class, dimensional standard, welding scope, heat treatment, and required test documents.
This page avoids universal service claims. S32750 selection should be checked against the actual chloride level, temperature, oxygen content, pH, sour-service condition, fabrication route, and governing code.
Chemical composition
Published chemistry reference.
The published chemistry values are structured data and must be reconciled against the actual material certificate for every supplied lot.
| Element | Verified nominal composition | Basis |
|---|---|---|
| Carbon | <=0.030 | Mass % |
| Silicon | <=0.8 | Mass % |
| Manganese | <=1.2 | Mass % |
| Phosphorus | <=0.025 | Mass % |
| Sulfur | <=0.015 | Mass % |
| Chromium | 25 | Mass % |
| Nickel | 7 | Mass % |
| Molybdenum | 4 | Mass % |
| Nitrogen | 0.3 | Mass % |
Mechanical properties
Verified property data.
Mechanical values are presented with product-form context. Flanges and fittings still follow the ordered ASTM or ASME route.
| Property | Metric | Imperial | Condition |
|---|---|---|---|
| Proof strength Rp0.2 | >=550 MPa | >=80 ksi | Solution annealed |
| Proof strength Rp1.0 | >=640 MPa | >=93 ksi | Solution annealed |
| Tensile strength Rm | 800-1000 MPa | 116-145 ksi | Solution annealed |
| Elongation A / A2 in | >=25% / >=15% | >=25% / >=15% | Solution annealed |
| Hardness | <=32 HRC | <=32 HRC | Solution annealed |
Corrosion behaviour
Selection guidance for the corrosion mechanism, not just the alloy name.
These notes are intentionally conservative because medium chemistry, temperature, stress, crevices, fabrication, and cleaning practice govern final suitability.
Chloride stress corrosion cracking
The super duplex structure is selected for strong chloride SCC resistance where austenitic stainless grades require caution.
Pitting and crevice corrosion
High chromium, molybdenum, and nitrogen content supports excellent resistance to localized corrosion in chloride-bearing process and seawater applications.
Organic and inorganic acids
Published guidance positions SAF 2507 for organic-acid service and for certain inorganic-acid concentration ranges, especially where chloride contamination is present.
Erosion corrosion and fatigue
Its strength and corrosion resistance make it relevant to seawater flow, solids exposure, and mechanically demanding systems.
Available RTI products
Flanges and pipe fittings routed by material standard.
The page template separates product form, material route, dimensional standard, inspection, and final release documents.
Flanges
Super Duplex 2507 flange enquiries should state ASTM A182 grade route, pressure class, facing, bore, heat treatment condition, PMI, and any project NORSOK/NACE requirements.
Pipe Fittings
Buttweld and forged fitting enquiries should distinguish forged fitting routes from wrought fitting routes, and should confirm class symbols, NDE, marking, and traceability before order release.
Relevant standards
Standards are supply routes, not decoration.
Each enquiry should identify which standard controls the product form, which standard controls dimensions, and which documents prove conformance.
ASTM A182 / ASME SA182
Forged or rolled alloy and stainless steel flanges, forged fittings, valves, and parts
ASTM A815 / ASME SA815
Wrought ferritic, ferritic-austenitic, and martensitic stainless steel piping fittings
ASTM A789 / A790
Duplex/super duplex seamless and welded tube and pipe references
ASTM A240
Plate, sheet, and strip reference
ASTM A479
Bar steel reference
NACE MR0175 / ISO 15156
Sour-service cracking-resistant CRA review where project conditions require it
Applications
Where procurement conversations usually begin.
Applications are signals for engineering review, documentation scope, and grade comparison.
Typical industries
Built for severe-service buying environments.
The same grade can behave differently by industry because service media, inspection plans, and owner specifications change.
Quality and inspection
Document control from the first quotation.
For critical alloys, inspection and certificate requirements belong in the RFQ, not as an afterthought before dispatch.
PMI
PMI is useful for separating S32750 from 2205, 316L, 904L, 6Mo, and nickel alloy items in mixed project packages.
MTC
The MTC should confirm UNS, heat number, solution annealing, chemical analysis, mechanical properties, and applicable standard/class.
EN 10204 3.1
Specify EN 10204 3.1 certification where buyer document control requires traceable inspection certificate release.
TPI
For critical offshore and desalination packages, define third-party witness points for dimensions, marking, PMI, packing, and document review.
NACE
NACE MR0175 / ISO 15156 requirements should be reviewed against sour-service limits, hardness, product form, heat treatment, and project specification.
IGC
Intergranular corrosion testing should be addressed when project standards request it for duplex stainless steel production or welding controls.
Material comparison
Compare material considerations before approving substitution.
This section frames substitution as an engineering decision, especially where corrosion mechanism, temperature, weld route, or code requirements change.
| Comparison | Super Duplex 2507 | Alternate route | Procurement consideration |
|---|---|---|---|
| Versus 316L | Far higher proof strength and chloride-localized-corrosion resistance | 316L is simpler and economical for moderate corrosion duty | Move to S32750 when chloride temperature, SCC risk, or load makes 316L marginal |
| Versus Inconel 625 | High-strength duplex stainless route for chloride service | Inconel 625 gives nickel alloy chemistry and broader severe chemical/elevated-temperature positioning | Compare corrosion mechanism, code stress, temperature, sour-service rules, and galvanic design |
| Versus Duplex 2205 | Higher alloyed 25Cr super duplex selection with stronger chloride-service positioning | 2205 is a common duplex option for less severe chloride duty | Ask the engineer for chloride, temperature, pH, oxygen, and cleaning chemistry before substitution |
Procurement guidance
The RFQ fields that prevent expensive ambiguity.
A strong alloy enquiry names the grade, standard, dimensions, inspection, documentation, packing, and destination before commercial comparison.
01
State UNS S32750 and avoid relying only on the commercial name 2507.
02
Separate flange route, forged fitting route, and wrought fitting route because ASTM A182 and ASTM A815 answer different supply questions.
03
Ask for solution annealing confirmation and heat-number traceability on the MTC.
04
For offshore or sour-service projects, add NACE, hardness, PMI, TPI, NDE, ferrite, and IGC clauses when required by the project specification.
05
Do not approve substitution from S32750 to 2205, 316L, 904L, or 6Mo without engineering review.
Engineering FAQs
Questions buyers and materials engineers should settle early.
FAQ content is unique to each benchmark material and remains tied to verified structured guidance.
Related materials
Continue the grade comparison.
Internal links connect related alloy families, technical guidance, and RFQ preparation.
Related technical guides
Procurement knowledge paths.
These connect material selection to document control, testing, quality review, and RFQ completeness.
Grade and product route review
Inspection and certificate planning
Traceable quotation package
Structured RFQ
Prepare a cleaner component enquiry
Capture material, standard, dimensions, quantity, inspection, documentation, packing, and destination before the technical quotation is prepared.
