Super Duplex 2507 FastenersUNS S32750 · Manufacturer, trader & 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 — available in this alloy. ASTM A1082 (S32750) where specified for applicable duplex bolts, studs, cap screws and nuts; for other types, material may be supplied to ASTM A276 / A479 bar where applicable, subject to the purchase specification. Dimensions to ASME B18 where applicable, or your drawing. State the finished fastener specification your project requires on the order. It is a super duplex stainless steel, chosen for seawater and high-chloride service where strength also matters. Kanak Steel & Engineering Co. manufactures, trades and exports it from Mumbai; EN 10204 3.1 or 3.2 certificates are available on request / as specified in the PO. Markets we have supplied to include Oman, UAE, Saudi Arabia, Brazil, Argentina, Spain and Chile (India is the home market).
- Stock & mill supply
- EN 10204 3.1 / 3.2
- PMI 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 (UNS S32750). ASTM A1082 (S32750) where specified for applicable duplex bolts, studs, cap screws and nuts; for other types, material may be supplied to ASTM A276 / A479 bar where applicable, subject to the purchase specification. 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
- Material
- ASTM A1082 (S32750) where specified for applicable duplex bolts, studs, cap screws and nuts; for other types, material may be supplied to ASTM A276 / A479 bar where applicable, subject to the purchase specification
- Feedstock (bar)
- ASTM A276 / A479, where applicable
- 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 A1082 (S32750) where specified for applicable duplex bolts, studs, cap screws and nuts; for other types, material may be supplied to ASTM A276 / A479 bar where applicable, subject to the purchase specification |
|---|---|
| Material / feedstock | ASTM A276 / A479 — a bar specification, where applicable; it covers the bar, not the finished fastener |
| Manufacturing route | By type: bolts, studs, cap screws and nuts may be machined from bar, where applicable; threaded rod, U-bolts, eye bolts, anchor and foundation bolts are route-dependent; washers not asserted — all to the purchase specification or project drawing |
| Dimensional standards | ASME B18.2.1 (bolts) · B18.2.2 (nuts) · B18.31.2 (studs) · DIN 931 / 933 / 934 (legacy DIN) |
| 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 Stud Bolts: Grade & Nut Pairing
Super Duplex 2507 studs and nuts may be machined from ASTM A276 / A479 bar, where applicable; the finished fastener specification is to the purchase specification or project drawing, and the nut is usually the same alloy.
Torque (T = K × F × d), stud length and coatings are covered in the fasteners guide.
| Galling | Stainless and nickel-alloy threads gall — always use anti-seize, and avoid high-speed tightening |
|---|---|
| Coatings | Usually supplied plain; PTFE coating on request to ease tightening |
| Marking | Grade symbol and maker's mark on each stud end and nut, as the standard requires |
| Certificates | EN 10204 3.1 for the bar heat; mechanical test reports on the finished bolts on request |
Super Duplex 2507 Fasteners Chemical Composition
Under technical review for TDS.
| Element | Current requirement |
|---|---|
| Chromium | As specified |
| Nickel | As specified |
| Molybdenum | As specified |
| Nitrogen | As specified |
| Copper | As specified |
| Carbon | As specified |
| Manganese | As specified |
| Silicon | As specified |
| Phosphorus | As specified |
| Sulphur | As specified |
| Iron | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification to be verified: ASTM A240 for UNS S32750.
Super Duplex 2507 Fasteners Mechanical Properties
Under technical review for TDS.
| Property | Current requirement |
|---|---|
| Tensile strength | As specified |
| Yield strength 0.2% | As specified |
| Elongation | As specified |
| Hardness | As specified |
Numerical specification requirements are published only after the applicable current standard edition has been verified. Governing specification and condition to be verified: ASTM A240 for UNS S32750 — Solution-annealed plate & sheet.
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
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. PMI can be arranged on request — state it on your enquiry.
Under technical review for TDS.
| Element | Super Duplex 2507 | Duplex 2205 |
|---|---|---|
| Nickel | As specified | As specified |
| Chromium | As specified | As specified |
| Molybdenum | As specified | As specified |
| Copper | As specified | — |
| Iron | As specified | As specified |
| Manganese | As specified | As specified |
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 A1082 (S32205) where specified for applicable duplex bolts, studs, cap screws and nuts; for other types, material may be supplied to ASTM A276 / A479 bar where applicable, subject to the purchase specification | ≈ 35 | Strength with chloride resistance at a stainless-steel budget |
| Super Duplex 2507 | ASTM A1082 (S32750) where specified for applicable duplex bolts, studs, cap screws and nuts; for other types, material may be supplied to ASTM A276 / A479 bar where applicable, subject to the purchase specification | ≈ 42 | Seawater and high-chloride service where strength also matters |
| Inconel 625 | ASTM F468 (N06625) where specified for applicable bolts, hex cap screws, socket-head cap screws and studs (0.250–1.500 in.), and ASTM F467 for applicable nuts (0.250–1.500 in.); for other types, material may be supplied to ASTM B446 bar where applicable, subject to the purchase specification | ≈ 51 | Seawater, high strength and high temperature in one alloy |
| Hastelloy C276 | ASTM F468 (N10276) where specified for applicable bolts, hex cap screws, socket-head cap screws and studs (0.250–1.500 in.), and ASTM F467 for applicable nuts (0.250–1.500 in.); for other types, material may be supplied to ASTM B574 bar where applicable, subject to the purchase specification | ≈ 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.
Much higher yield strength than 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 against your order; PMI can be arranged depending on product and requirements, as specified in the PO.
- 03Processing — cutting, machining or bevelling to your specification, with heat numbers marked as specified in the PO.
- 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.
Standards on this page
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 | Thermal or abrasive cutting; 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 — questions buyers ask
Is Super Duplex 2507 the same as UNS S32750?
UNS S32750, W.Nr 1.4410, F53 are names used for Super Duplex 2507 (W.Nr / EN numbers and older UNS variants are the closest designations; their limits can differ slightly, so specify the UNS number and ASTM grade on the order). Whichever name is on the enquiry, fasteners: ASTM A1082 (S32750) where specified for applicable duplex bolts, studs, cap screws and nuts.
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.
What nut goes with Super Duplex 2507 stud bolts?
Usually a heavy hex nut in the same Super Duplex 2507 alloy — it may be machined from ASTM A276 / A479 bar, where applicable; finished requirements are to the purchase specification or project drawing.
How do I stop Super Duplex 2507 bolts galling?
Use an anti-seize compound on threads and nut faces, tighten at moderate speed, and do not reuse galled nuts.
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