Inconel 718 FastenersASTM B637 UNS N07718 · Manufacturer, stockist & exporter, India
Also sold as Alloy 718 · UNS N07718 · W.Nr 2.4668 · Precipitation-hardening nickel alloy
Inconel 718 fasteners — stud bolts, hex bolts, nuts and washers — are made from ASTM B637 bar stock to ASME B18 dimensions. It is a age-hardenable nickel–chromium alloy with niobium and molybdenum, chosen for very high strength at temperatures up to about 650 °C. 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 718 Fasteners?
Inconel 718 fasteners is an age-hardenable nickel–chromium alloy with niobium and molybdenum supplied as fasteners to ASTM B637 (UNS N07718). Buyers specify it for very high strength at temperatures up to about 650 °C. It is also sold as Alloy 718, UNS N07718, W.Nr 2.4668.
- What it is
- Age-hardenable nickel–chromium alloy with niobium and molybdenum
- Bar stock
- ASTM B637
- Dimensions
- ASME B18.2.1 · B18.2.2 · B18.31.2
- Threads
- UNC · UN-8 · metric
- Sizes
- M10 – M64 · ½" – 4"
- Best at
- Very high strength at temperatures up to about 650 °C
Inconel 718 Fasteners Specification & Sizes
| Material | ASTM B637 |
|---|---|
| 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 718 Stud Bolts: Grade & Nut Pairing
Inconel 718 studs and nuts are machined from ASTM B637 bar; the nut is usually the same alloy. Bolts are normally supplied solution treated and aged (e.g. AMS 5663) for full strength; AMS 5662 is the solution-treated condition — state the condition on the order.
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 718 Fasteners Chemical Composition
| Element | Weight % |
|---|---|
| Nickel (+Co) | 50.0 – 55.0 |
| Chromium | 17.0 – 21.0 |
| Niobium + Tantalum | 4.75 – 5.50 |
| Molybdenum | 2.80 – 3.30 |
| Titanium | 0.65 – 1.15 |
| Aluminium | 0.20 – 0.80 |
| Carbon | 0.08 max |
| Iron | Balance |
Inconel 718 Fasteners Mechanical Properties
| Solution-treated and aged | Value |
|---|---|
| Tensile strength | 1275 MPa · 185 ksi |
| Yield strength 0.2% | 1034 MPa · 150 ksi |
| Elongation | 12% |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8.19 g/cm³ |
| Melting range | 1260 – 1336 °C |
| Magnetic | Non-magnetic |
Inconel 718 Equivalent Grades
Values follow ASTM B637 / B670 for UNS N07718. 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 718 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 718 is most often mixed up with Inconel 625 — 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 718 | Inconel 625 |
|---|---|---|
| Nickel | 50.0 – 55.0 | 58.0 min |
| Chromium | 17.0 – 21.0 | 20.0 – 23.0 |
| Molybdenum | 2.80 – 3.30 | 8.0 – 10.0 |
| Titanium | 0.65 – 1.15 | 0.40 max |
| Niobium | 4.75 – 5.50 | 3.15 – 4.15 |
| Iron | Balance | 5.0 max |
| Manganese | residual | 0.50 max |
Inconel 718 fasteners by type
Inconel 718 Fasteners Applications
Inconel 718 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 718 Fasteners vs 625, 600 and 825
| Grade | Fasteners standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| Inconel 600 | ASTM B166 | — | High-temperature oxidation, caustic and nuclear service |
| Inconel 718 | ASTM B637 | — | Very high strength at temperatures up to about 650 °C |
| Inconel 825 | ASTM B425 | ≈ 31 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| Inconel 625 | ASTM B446 | ≈ 51 | Seawater, high strength and high temperature in one alloy |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
Inconel 718 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 718 fits.
Niobium forms the gamma-double-prime phase that doubles strength after ageing.
Keeps very high strength and creep resistance up to about 650 °C.
Ages slowly, so it can be welded without cracking during post-weld heat treatment.
718 is chosen for strength; for corrosion alone, 625 or 825 are usually better value.
How your 718 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 718 Fasteners
Inconel 718 welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ERNiFeCr-2 (AWS A5.14) |
|---|---|
| Over-alloyed filler | Post-weld solution treatment and ageing restore strength |
| 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 718 fittings and 718 flanges for the matching pipe-system parts.
How to Order Inconel 718 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 718 fasteners for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiInconel 718 fasteners — questions buyers ask
Is Inconel 718 the same as Alloy 718?
Yes. Alloy 718, UNS N07718, W.Nr 2.4668 all refer to the same material, and fasteners is ordered to ASTM B637 whichever name is on the enquiry.
Why use Inconel 718 bolts instead of B7 carbon steel?
On Inconel 718 flanges in corrosive service, carbon-steel bolts corrode first. Matching-alloy bolting avoids galvanic corrosion and bolt failure.
What nut goes with Inconel 718 stud bolts?
A heavy hex nut machined from the same Inconel 718 bar (ASTM B637), unless the project specifies otherwise.
How do I stop Inconel 718 bolts galling?
Use an anti-seize compound on threads and nut faces, tighten at moderate speed, and do not reuse galled nuts.
Inconel 718 or Inconel 825 — which should I choose?
Inconel 718 is chosen for very high strength at temperatures up to about 650 °C. Inconel 825 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