Inconel 825 / Incoloy 825 FastenersASTM B425 UNS N08825 · Manufacturer, stockist & exporter, India
Also sold as Incoloy 825 · Alloy 825 · UNS N08825 · W.Nr 2.4858
Inconel 825 fasteners — stud bolts, hex bolts, nuts and washers — are made from ASTM B425 bar stock to ASME B18 dimensions. It is a nickel–iron–chromium alloy with molybdenum, copper and titanium, chosen for sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas. 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 825 Fasteners?
Inconel 825 fasteners is a nickel–iron–chromium alloy with molybdenum, copper and titanium supplied as fasteners to ASTM B425 (UNS N08825). Buyers specify it for sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas. It is also sold as Incoloy 825, Alloy 825, UNS N08825.
- What it is
- Nickel–iron–chromium alloy with molybdenum, copper and titanium
- Bar stock
- ASTM B425
- Dimensions
- ASME B18.2.1 · B18.2.2 · B18.31.2
- Threads
- UNC · UN-8 · metric
- Sizes
- M10 – M64 · ½" – 4"
- Best at
- Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas
Inconel 825 Fasteners Specification & Sizes
| Material | ASTM B425 |
|---|---|
| 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 825 Stud Bolts: Grade & Nut Pairing
Inconel 825 studs and nuts are machined from ASTM B425 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 825 Fasteners Chemical Composition
| Element | Weight % |
|---|---|
| Nickel | 38.0 – 46.0 |
| Iron | 22.0 min |
| Chromium | 19.5 – 23.5 |
| Molybdenum | 2.5 – 3.5 |
| Copper | 1.5 – 3.0 |
| Titanium | 0.6 – 1.2 |
| Carbon | 0.05 max |
| Manganese | 1.0 max |
| Silicon | 0.5 max |
| Aluminium | 0.2 max |
| Sulphur | 0.03 max |
Inconel 825 Fasteners Mechanical Properties
| Annealed | Value |
|---|---|
| Tensile strength | 586 MPa · 85 ksi |
| Yield strength 0.2% | 241 MPa · 35 ksi |
| Elongation | 30% |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8.14 g/cm³ |
| Melting range | 1370 – 1400 °C |
| Magnetic | Non-magnetic (annealed) |
| PREN (approx.) | ≈ 31 |
Inconel 825 Equivalent Grades
Values follow ASTM B424 / B423 / B564 for UNS N08825. 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 825 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 825 is most often mixed up with SS 904L — 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 825 | SS 904L |
|---|---|---|
| Nickel | 38.0 – 46.0 | 23.0 – 28.0 |
| Chromium | 19.5 – 23.5 | 19.0 – 23.0 |
| Molybdenum | 2.5 – 3.5 | 4.0 – 5.0 |
| Copper | 1.5 – 3.0 | 1.0 – 2.0 |
| Titanium | 0.6 – 1.2 | residual |
| Iron | 22.0 min | Balance |
| Manganese | 1.0 max | 2.00 max |
Inconel 825 fasteners by type
Inconel 825 Fasteners Applications
Inconel 825 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 825 Fasteners vs 316L, 904L and 625
| Grade | Fasteners standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| SS 316 / 316L | ASTM A193 B8M · A194 8M | ≈ 24 | Chloride-bearing process fluids, marine air and pharmaceutical service |
| Inconel 825 | ASTM B425 | ≈ 31 | Sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas |
| SS 904L | ASTM B649 | ≈ 35 | Dilute sulphuric acid, phosphoric acid and chloride-bearing cooling water |
| 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 825 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 825 fits.
Around 40% nickel takes the alloy well clear of the range where austenitic stainless steels crack in hot chlorides.
Molybdenum and copper give 825 its standing in sulphuric and phosphoric acid service, and help against pitting.
About 21% chromium handles nitric acid, nitrates and oxidising salts.
Titanium stabilises the alloy, so welded parts resist sensitisation in the heat-affected zone.
How your 825 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 825 Fasteners
Inconel 825 welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ERNiFeCr-1 (AWS A5.14) |
|---|---|
| Over-alloyed filler | ERNiCrMo-3 wire · 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 825 fittings and 825 flanges for the matching pipe-system parts.
How to Order Inconel 825 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 825 fasteners for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiInconel 825 fasteners — questions buyers ask
Is Inconel 825 the same as Incoloy 825?
Yes. Incoloy 825, Alloy 825, UNS N08825 all refer to the same material, and fasteners is ordered to ASTM B425 whichever name is on the enquiry.
Why use Inconel 825 bolts instead of B7 carbon steel?
On Inconel 825 flanges in corrosive service, carbon-steel bolts corrode first. Matching-alloy bolting avoids galvanic corrosion and bolt failure.
What nut goes with Inconel 825 stud bolts?
A heavy hex nut machined from the same Inconel 825 bar (ASTM B425), unless the project specifies otherwise.
How do I stop Inconel 825 bolts galling?
Use an anti-seize compound on threads and nut faces, tighten at moderate speed, and do not reuse galled nuts.
Inconel 825 or Inconel 625 — which should I choose?
Inconel 825 is chosen for sulphuric and phosphoric acid service, chloride stress-corrosion cracking and sour gas. Inconel 625 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