Monel K500 FastenersASTM B865 UNS N05500 · Manufacturer, stockist & exporter, India
Also sold as Alloy K-500 · UNS N05500 · W.Nr 2.4375 · Age-hardened Monel
Monel K500 fasteners — stud bolts, hex bolts, nuts and washers — are made from ASTM B865 bar stock to ASME B18 dimensions. It is a age-hardenable nickel–copper alloy with aluminium and titanium, chosen for high-strength pump shafts, bolting and springs in seawater. 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 Monel K500 Fasteners?
Monel K500 fasteners is an age-hardenable nickel–copper alloy with aluminium and titanium supplied as fasteners to ASTM B865 (UNS N05500). Buyers specify it for high-strength pump shafts, bolting and springs in seawater. It is also sold as Alloy K-500, UNS N05500, W.Nr 2.4375.
- What it is
- Age-hardenable nickel–copper alloy with aluminium and titanium
- Bar stock
- ASTM B865
- Dimensions
- ASME B18.2.1 · B18.2.2 · B18.31.2
- Threads
- UNC · UN-8 · metric
- Sizes
- M10 – M64 · ½" – 4"
- Best at
- High-strength pump shafts, bolting and springs in seawater
Monel K500 Fasteners Specification & Sizes
| Material | ASTM B865 |
|---|---|
| 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 |
Monel K500 Stud Bolts: Grade & Nut Pairing
Monel K500 studs and nuts are machined from ASTM B865 bar; the nut is usually the same alloy. K-500 bolting is supplied age-hardened for strength; state the condition and hardness limit.
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 |
Monel K500 Fasteners Chemical Composition
| Element | Weight % |
|---|---|
| Nickel (+Co) | 63.0 min |
| Copper | 27.0 – 33.0 |
| Aluminium | 2.30 – 3.15 |
| Titanium | 0.35 – 0.85 |
| Iron | 2.0 max |
| Manganese | 1.5 max |
| Carbon | 0.25 max |
| Silicon | 0.5 max |
Monel K500 Fasteners Mechanical Properties
| Age-hardened bar | Value |
|---|---|
| Tensile strength | 965 MPa · 140 ksi |
| Yield strength 0.2% | 690 MPa · 100 ksi |
| Elongation | 20% |
Density & Physical Properties
| Property | Value |
|---|---|
| Density | 8.44 g/cm³ |
| Melting range | 1315 – 1350 °C |
| Magnetic | Non-magnetic to about −100 °C |
Monel K500 Equivalent Grades
Values follow ASTM B865 for UNS N05500. 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 Monel K500 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. Monel K500 is most often mixed up with Monel 400 — 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 | Monel K500 | Monel 400 |
|---|---|---|
| Nickel | 63.0 min | 63.0 min |
| Copper | 27.0 – 33.0 | 28.0 – 34.0 |
| Titanium | 0.35 – 0.85 | residual |
| Iron | 2.0 max | 2.5 max |
| Manganese | 1.5 max | 2.0 max |
Monel K500 fasteners by type
Monel K500 Fasteners Applications
Monel K500 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.
Monel K500 Fasteners vs 400, 718 and 2507
| Grade | Fasteners standard | PREN (approx.) | Pick it when |
|---|---|---|---|
| Monel 400 | ASTM B164 | — | Seawater, hydrofluoric acid and marine service |
| Inconel 718 | ASTM B637 | — | Very high strength at temperatures up to about 650 °C |
| Monel K500 | ASTM B865 | — | High-strength pump shafts, bolting and springs in seawater |
| Super Duplex 2507 | ASTM A276 / A479 | ≈ 42 | Seawater and high-chloride service where strength also matters |
PREN = Cr + 3.3 Mo + 16 N, from mid-range chemistry. A screening guide, not a substitute for corrosion data on your medium.
Monel K500 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 K500 fits.
Aluminium and titanium let K500 be age-hardened to about three times the strength of Monel 400.
Keeps the seawater corrosion resistance of Monel 400.
Chosen where a part needs strength and seawater resistance together.
In sour service, check hardness limits in NACE MR0175 before specifying.
How your K500 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 Monel K500 Fasteners
Monel K500 welds by all common arc processes. A few points our buyers ask about:
| Matching filler | ERNiCu-7 (non-ageing) |
|---|---|
| Over-alloyed filler | Weld in the annealed condition, then age |
| 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.
How to Order Monel K500 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
Monel K500 fasteners for export
FOB / CIF · Nhava Sheva (JNPT), MumbaiMonel K500 fasteners — questions buyers ask
Is Monel K500 the same as Alloy K-500?
Yes. Alloy K-500, UNS N05500, W.Nr 2.4375 all refer to the same material, and fasteners is ordered to ASTM B865 whichever name is on the enquiry.
Why use Monel K500 bolts instead of B7 carbon steel?
On Monel K500 flanges in corrosive service, carbon-steel bolts corrode first. Matching-alloy bolting avoids galvanic corrosion and bolt failure.
What nut goes with Monel K500 stud bolts?
A heavy hex nut machined from the same Monel K500 bar (ASTM B865), unless the project specifies otherwise.
How do I stop Monel K500 bolts galling?
Use an anti-seize compound on threads and nut faces, tighten at moderate speed, and do not reuse galled nuts.
Monel K500 or Super Duplex 2507 — which should I choose?
Monel K500 is chosen for high-strength pump shafts, bolting and springs in seawater. Super Duplex 2507 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