Inconel 625 FastenersASTM B446 UNS N06625 · Manufacturer, stockist & exporter, India
Also sold as Alloy 625 · UNS N06625 · W.Nr 2.4856 · Nicrofer 6020
Inconel 625 fasteners — stud bolts, hex bolts, nuts and washers — are made from ASTM B446 bar stock to ASME B18 dimensions. It is a nickel–chromium–molybdenum alloy with niobium, chosen for seawater, high strength and high temperature in one alloy. 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 Inconel 625 Fasteners?
Inconel 625 fasteners is a nickel–chromium–molybdenum alloy with niobium supplied as fasteners to ASTM B446 (UNS N06625). Buyers specify it for seawater, high strength and high temperature in one alloy. It is also sold as Alloy 625, UNS N06625, W.Nr 2.4856.
- What it is
- Nickel–chromium–molybdenum alloy with niobium
- Bar stock
- ASTM B446
- Dimensions
- ASME B18.2.1 · B18.2.2 · B18.31.2
- Threads
- UNC · UN-8 · metric
- Sizes
- M10 – M64 · ½" – 4"
- Best at
- Seawater, high strength and high temperature in one alloy
Inconel 625 Fasteners Specification & Sizes
| Material | ASTM B446 |
|---|---|
| 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 |
Inconel 625 Stud Bolts: Grade & Nut Pairing
Inconel 625 studs and nuts are machined from ASTM B446 bar; 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 |
Inconel 625 Fasteners Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | 58.0 min |
| Chromium | 20.0 – 23.0 |
| Molybdenum | 8.0 – 10.0 |
| Niobium + Tantalum | 3.15 – 4.15 |
| Iron | 5.0 max |
| Carbon | 0.10 max |
| Manganese | 0.50 max |
| Silicon | 0.50 max |
| Titanium | 0.40 max |
| Aluminium | 0.40 max |
Inconel 625 Fasteners Mechanical Properties
| Grade 1 annealed plate | Value |
|---|---|
| Tensile strength | 827 MPa · 120 ksi |
| Yield strength 0.2% | 414 MPa · 60 ksi |
| Elongation | 30% |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8.44 g/cm³ |
| Melting range | 1290 – 1350 °C |
| Magnetic | Non-magnetic |
| PREN (approx.) | ≈ 51 |
Inconel 625 Equivalent Grades
Values follow ASTM B443 for UNS N06625. Always check against the edition named on your purchase order.
Six-digit Harmonized System heading (nickel alloy, chapter 75). Your country adds its own digits — confirm with your customs broker. All HS codes.
How to Verify Inconel 625 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. Inconel 625 is most often mixed up with Hastelloy C276 — the table shows which elements tell them apart.
Handheld XRF does not measure carbon or nitrogen; those come from the mill certificate or optical emission (OES) testing. We PMI-test nickel alloys as standard and any grade on request.
| Element | Inconel 625 | Hastelloy C276 |
|---|---|---|
| Nickel | 58.0 min | Balance |
| Chromium | 20.0 – 23.0 | 14.5 – 16.5 |
| Molybdenum | 8.0 – 10.0 | 15.0 – 17.0 |
| Titanium | 0.40 max | residual |
| Niobium | 3.15 – 4.15 | residual |
| Tungsten | residual | 3.0 – 4.5 |
| Iron | 5.0 max | 4.0 – 7.0 |
| Manganese | 0.50 max | 1.0 max |
Inconel 625 fasteners by type
Inconel 625 Fasteners Applications
Inconel 625 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.
Inconel 625 Fasteners vs 825, 2507 and C276
| Grade | Fasteners standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| Inconel 825 | ASTM B425 | ≈ 31 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| 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.
Inconel 625 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 625 fits.
About 9% molybdenum gives PREN above 50 — seawater pitting is rarely a concern.
Niobium strengthens the matrix without heat treatment: yield about 414 MPa annealed.
High nickel makes it virtually immune to chloride stress-corrosion cracking.
Keeps useful strength and oxidation resistance at high temperature.
How your 625 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 Inconel 625 Fasteners
Inconel 625 welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ERNiCrMo-3 (AWS A5.14) |
|---|---|
| Over-alloyed filler | ENiCrMo-3 electrode |
| 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 625 fittings and 625 flanges for the matching pipe-system parts.
How to Order Inconel 625 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
Inconel 625 fasteners for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiInconel 625 fasteners — questions buyers ask
Is Inconel 625 the same as Alloy 625?
Yes. Alloy 625, UNS N06625, W.Nr 2.4856 all refer to the same material, and fasteners is ordered to ASTM B446 whichever name is on the enquiry.
Why use Inconel 625 bolts instead of B7 carbon steel?
On Inconel 625 flanges in corrosive service, carbon-steel bolts corrode first. Matching-alloy bolting avoids galvanic corrosion and bolt failure.
What nut goes with Inconel 625 stud bolts?
A heavy hex nut machined from the same Inconel 625 bar (ASTM B446), unless the project specifies otherwise.
How do I stop Inconel 625 bolts galling?
Use an anti-seize compound on threads and nut faces, tighten at moderate speed, and do not reuse galled nuts.
Inconel 625 or Hastelloy C276 — which should I choose?
Inconel 625 is chosen for seawater, high strength and high temperature in one alloy. 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