Super Duplex 2507 FastenersASTM A276 UNS S32750 · Manufacturer, stockist & exporter, India
Also sold as UNS S32750 · W.Nr 1.4410 · F53 · SAF 2507
Super Duplex 2507 fasteners — stud bolts, hex bolts, nuts and washers — are made from ASTM A276 / A479 bar stock to ASME B18 dimensions. It is a super duplex stainless steel, chosen for seawater and high-chloride service where strength also matters. Kanak Steel & Engineering Co. supplies it with EN 10204 3.1 mill certificates from Mumbai to buyers across India, the Gulf, South-East Asia, South America, Europe, the UK and the USA.
- Stock & mill supply
- EN 10204 3.1 / 3.2
- PMI on every heat
- NACE MR0175 on request
- Export packing
Reviewed by the Kanak Steel & Engineering Co. technical team · Updated October 2026
What is Super Duplex 2507 Fasteners?
Super Duplex 2507 fasteners is a super duplex stainless steel supplied as fasteners to ASTM A276 / A479 (UNS S32750). Buyers specify it for seawater and high-chloride service where strength also matters. It is also sold as UNS S32750, W.Nr 1.4410, F53.
- What it is
- Super duplex stainless steel
- Bar stock
- ASTM A276 / A479
- Dimensions
- ASME B18.2.1 · B18.2.2 · B18.31.2
- Threads
- UNC · UN-8 · metric
- Sizes
- M10 – M64 · ½" – 4"
- Best at
- Seawater and high-chloride service where strength also matters
Super Duplex 2507 Fasteners Specification & Sizes
| Material | ASTM A276 / A479 |
|---|---|
| Dimensional standards | ASME B18.2.1 (bolts) · B18.2.2 (nuts) · B18.31.2 (studs) · DIN 931 / 933 / 934 |
| Types | Stud bolt · Hex bolt · Heavy hex nut · Hex nut · Washer · Threaded rod · U-bolt · Eye bolt · Anchor bolt · Foundation bolt · Socket head cap screw · Machine screw |
| Threads | UNC, UN-8 and metric coarse |
| Coating | Plain · PTFE on request |
| Documents | EN 10204 3.1 |
Super Duplex 2507 Fasteners Chemical Composition
| Element | Weight % |
|---|---|
| Chromium | 24.0 – 26.0 |
| Nickel | 6.0 – 8.0 |
| Molybdenum | 3.0 – 5.0 |
| Nitrogen | 0.24 – 0.32 |
| Copper | 0.50 max |
| Carbon | 0.030 max |
| Manganese | 1.20 max |
| Silicon | 0.80 max |
| Phosphorus | 0.035 max |
| Sulphur | 0.020 max |
| Iron | Balance |
Super Duplex 2507 Fasteners Mechanical Properties
| Solution-annealed plate & sheet | Value |
|---|---|
| Tensile strength | 795 MPa · 116 ksi |
| Yield strength 0.2% | 550 MPa · 80 ksi |
| Elongation | 15% |
| Hardness | 310 HB max |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 7.8 g/cm³ |
| Melting range | 1350 – 1400 °C |
| Magnetic | Magnetic (ferritic phase) |
| PREN (approx.) | ≈ 42 |
Super Duplex 2507 Equivalent Grades
Values follow ASTM A240 for UNS S32750. Always check against the edition named on your purchase order.
Six-digit Harmonized System heading (iron and steel, chapter 72–73). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify Super Duplex 2507 Fasteners with PMI
Positive material identification with a handheld XRF gun confirms the alloy on the piece itself, in seconds, before it is cut or welded. Super Duplex 2507 is most often mixed up with Duplex 2205 — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen, so it cannot confirm the nitrogen that duplex depends on: that comes from the mill certificate or optical emission (OES) testing. We PMI-test nickel alloys as standard and any grade on request.
| Element | Super Duplex 2507 | Duplex 2205 |
|---|---|---|
| Nickel | 6.0 – 8.0 | 4.5 – 6.5 |
| Chromium | 24.0 – 26.0 | 22.0 – 23.0 |
| Molybdenum | 3.0 – 5.0 | 3.0 – 3.5 |
| Copper | 0.50 max | residual |
| Iron | Balance | Balance |
| Manganese | 1.20 max | 2.00 max |
Super Duplex 2507 fasteners by type
Super Duplex 2507 Fasteners Applications
Super Duplex 2507 is specified when the cheaper grade will not survive the service but a higher alloy would be more than the job needs. These are the jobs our buyers use it for.
Super Duplex 2507 Fasteners vs 2205, 625 and C276
| Grade | Fasteners standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| Duplex 2205 | ASTM A276 / A479 | ≈ 35 | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 | ASTM A276 / A479 | ≈ 42 | Seawater and high-chloride service where strength also matters |
| Inconel 625 | ASTM B446 | ≈ 51 | Seawater, high strength and high temperature in one alloy |
| Hastelloy C276 | ASTM B574 | ≈ 68 | The most aggressive mixed acids, wet chlorine and hypochlorite |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
Super Duplex 2507 Corrosion Resistance — Element by Element
Each alloying addition has a job. Knowing which one protects against your medium is the quickest way to judge whether 2507 fits.
High chromium, molybdenum and nitrogen put PREN above 40 — the usual threshold for seawater service.
Yield strength around 550 MPa, more than twice 316L.
Excellent resistance to chloride stress-corrosion cracking.
Keep service below about 250 °C.
How your 2507 fasteners order runs
- 01Enquiry review — we confirm size, standard edition and documents against your MR or drawing.
- 02Heat selection & PMI — the mill certificate is checked and material is PMI-tested before processing.
- 03Processing — cutting, machining or bevelling to your specification, with heat numbers marked.
- 04Inspection — your third-party inspector witnesses, or we share photos and test reports.
- 05Packing & dispatch — seaworthy packing from Nhava Sheva (JNPT), Mumbai, FOB or CIF, documents sent before the vessel sails.
Welding & Fabricating Super Duplex 2507 Fasteners
Super Duplex 2507 welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ER2594 (AWS A5.9) |
|---|---|
| Over-alloyed filler | Tight heat-input control and ferrite checks on procedure qualification |
| Preheat | Not required; keep interpass temperature low |
| Cutting | Plasma or waterjet; grind off heat-tinted edges before welding |
Follow your approved WPS; this is general guidance. See also 2507 fittings and 2507 flanges for the matching pipe-system parts.
How to Order Super Duplex 2507 Fasteners: RFQ Checklist
Get an accurate quote the first time. Copy this list into your enquiry:
- Fastener type, size and length
- Thread form
- Material and marking
- Quantity in sets
- Certificate type
- Delivery port and date
Super Duplex 2507 fasteners for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiSuper Duplex 2507 fasteners — questions buyers ask
Is Super Duplex 2507 the same as UNS S32750?
Yes. UNS S32750, W.Nr 1.4410, F53 all refer to the same material, and fasteners is ordered to ASTM A276 / A479 whichever name is on the enquiry.
Why use Super Duplex 2507 bolts instead of B7 carbon steel?
On Super Duplex 2507 flanges in corrosive service, carbon-steel bolts corrode first. Matching-alloy bolting avoids galvanic corrosion and bolt failure.
Super Duplex 2507 or Hastelloy C276 — which should I choose?
Super Duplex 2507 is chosen for seawater and high-chloride service where strength also matters. Hastelloy C276 is the step up when you need more pitting resistance or strength. See the comparison table on this page, or ask us with your process conditions.
Sources: the ASTM / ASME specifications named on this page and producer datasheets · Last updated October 2026