Monel K500 Fasteners – K-500 Bolts, Nuts, Studs & Screws (ASTM F468)
What are Monel K500 fasteners?
They are bolts, nuts, studs, screws and washers made from Monel K-500 (UNS N05500, W.Nr. 2.4375) – a nickel-copper alloy with added aluminium and titanium that is age-hardened to about three times the yield strength of Monel 400, while keeping Monel’s excellent resistance to seawater. Bolts, screws and studs are supplied to ASTM F468 Grade 500 (marking F 468W) and nuts to ASTM F467, machined from ASTM B865 bar.
Monel K500 Fasteners – Quick Facts
- Alloy: Monel K-500, UNS N05500, DIN 2.4375 (NiCu30Al)
- Fastener standards: ASTM F468 / ASME SF468 (bolts, screws, studs), ASTM F467 / ASME SF467 (nuts)
- Raw material: ASTM B865 / ASME SB865 bar and rod
- Strength (F468, ¼”–⅞”): 130–180 ksi tensile, 90 ksi min yield, 24–37 HRC
- Types: hex and heavy hex bolts, studs, stud bolts, socket screws, nuts, washers, threaded rod
- Certificate: EN 10204 3.1 with hardness, tensile and chemistry
ASC LLP, Mumbai, supplies Monel K500 fasteners from stock and to drawing. See all Monel fasteners or the full Monel range.
Monel K500 Chemical Composition (UNS N05500)
| Element | Composition (wt %) |
| Nickel (Ni) | 63.0 – 70.0 |
| Copper (Cu) | Balance (≈ 27 – 33) |
| Aluminium (Al) | 2.30 – 3.15 |
| Titanium (Ti) | 0.35 – 0.85 |
| Iron (Fe) | 2.0 max |
| Manganese (Mn) | 1.5 max |
| Carbon (C) | 0.25 max |
| Silicon (Si) | 0.5 max |
| Sulphur (S) | 0.01 max |
The aluminium and titanium form fine Ni₃(Al,Ti) precipitates during age hardening – this is what gives K-500 its high strength. Corrosion resistance is essentially the same as Monel 400.
Mechanical Properties – ASTM F468 Grade 500
| Property | ASTM F468 Grade 500 (¼” – ⅞”) |
| Marking | F 468W |
| Hardness | 24 – 37 HRC |
| Full-size tensile strength | 130 – 180 ksi (896 – 1,241 MPa) |
| Full-size yield strength, min | 90 ksi (621 MPa) |
| Machined-specimen tensile, min | 130 ksi (896 MPa) |
| Elongation in 4D, min | 20% |
Requirements for age-hardened K-500 bolts, screws and studs per ASTM F468. Always state “F468 Grade 500” (or F467 for nuts) on the order so the correct age-hardening and marking are applied.
Monel K500 Fastener Specifications
| Standard | What it covers |
| ASTM F468 / ASME SF468 | Bolts, hex cap screws, socket screws and studs – Grade 500 for K-500 |
| ASTM F467 / ASME SF467 | Nuts – Grade 500 for K-500 |
| ASTM B865 / ASME SB865 | K-500 bar, rod, wire and forgings (raw material – not a fastener standard) |
| UNS / W.Nr. | N05500 / 2.4375 |
| Dimensions | ASME B18.2.1 / B18.2.2 / B18.3 / B18.31.2, ISO 4014, 4017, 4032, 4762 |
Types of Monel K500 Fasteners
| Fastener type | Typical use |
| Hex & heavy hex bolts | General marine and pump/valve bolting |
| Studs & stud bolts | Flange bolting to ASME B16.5 / B16.47 in seawater systems |
| Hex & heavy hex nuts (F467) | Matching nuts for K-500 bolts and studs |
| Socket head cap screws | Compact high-strength joints in pumps and instruments |
| Threaded rod | Cut-to-length studs and anchors |
| Washers & shoulder nuts | Bearing surfaces and special assemblies |
Monel K500 Fastener Sizes
| Fastener type | Size range | Length | Threads |
| Hex bolts | ¼” – 2″ (M6 – M52) | ½” – 12″ | UNC, UNF, 8UN, metric |
| Stud bolts | ¼” – 2½” | Any length | UNC, 8UN, metric |
| Nuts | ¼” – 2½” | – | UNC, UNF, 8UN, metric |
| Socket screws | #4 – 1½” | To 6″ | UNC, UNF, metric |
| Threaded rod | ¼” – 2″ | Up to 3 m | UNC, metric |
Non-standard diameters, lengths, threads and head styles are machined to drawing.
Monel K500 vs Monel 400 Fasteners
| Property | Monel 400 (F468 Grade 400) | Monel K-500 (F468 Grade 500) |
| Strengthening | Solid solution (cold work) | Age hardening (Ni₃(Al,Ti) precipitates) |
| Full-size tensile | 80 – 130 ksi | 130 – 180 ksi |
| Yield, min | 40 ksi | 90 ksi |
| Hardness | 75 HRB – 25 HRC | 24 – 37 HRC |
| Magnetic | Slightly magnetic at room temperature | Non-magnetic down to about −100 °C |
| Typical use | General seawater and HF service | High-strength subsea, pump and valve bolting |
Age hardening: K-500 fasteners are typically aged at about 595 °C (1,100 °F) for around 16 hours and slow-cooled, after machining or thread rolling. Welding or re-heating in service above the ageing temperature lowers the strength, so K-500 bolts should not be welded.
Physical Properties of Monel K-500
| Property | Value (approx.) |
| Density | 8.44 g/cm³ |
| Melting range | 1,315 – 1,350 °C |
| Modulus of elasticity | ≈ 179 GPa (26 × 10⁶ psi) |
| Thermal conductivity | ≈ 17 W/m·K |
| Magnetic | Non-magnetic down to about −100 °C |
Corrosion Resistance & Limits
- Seawater and brine: very low corrosion rates in flowing seawater; resistant to chloride stress-corrosion cracking.
- Hydrofluoric acid and alkalis: good resistance, similar to Monel 400.
- Stagnant seawater: can suffer pitting under deposits – design to avoid crevices and stagnant zones.
- Hydrogen embrittlement: high-hardness K-500 can be sensitive to hydrogen under cathodic protection; limit hardness (often to about 35 HRC or below) for subsea bolting as per project specification.
- Not for: oxidising acids (nitric), oxidising salts (ferric and cupric chlorides).
How to Order Monel K500 Fasteners
- Type and size: e.g. 7/8″-9 UNC stud bolt × 180 mm, or M20 × 80 hex bolt.
- Specification: ASTM F468 Grade 500 (bolts / studs) and ASTM F467 Grade 500 (nuts).
- Hardness limit: state any project maximum (for example for subsea cathodic protection).
- Coating: plain, or PTFE / Xylan coating if required.
- Documents: 3.1 certificate, hardness and proof-load results, third-party inspection if needed.
Other Monel grades: Monel 400 fasteners, Monel 405, Monel R-405 and Monel 401.
Applications of Monel K500 Fasteners
| Industry | Typical K-500 fastener uses |
| Offshore oil & gas | Subsea bolting, valve and wellhead fasteners |
| Marine & naval | Propeller, rudder and shaft fasteners, deck hardware |
| Pumps & valves | Pump shafts, impeller nuts, valve stem bolting in seawater |
| Desalination & power | Seawater pump and condenser fasteners |
| Chemical processing | High-strength bolting in HF and caustic service |
Why Buy Monel K500 Fasteners from ASC LLP?
- Correct spec and marking: F468 / F467 Grade 500, age-hardened, with hardness and tensile results on the 3.1 certificate.
- Full range: bolts, studs, nuts, socket screws, washers and threaded rod, imperial and metric.
- Matching Monel products: K-500 pipes, K-500 plates, K-500 flanges.
- Testing: PMI, hardness, tensile and proof-load; third-party inspection on request.
- Export packing and regular shipments worldwide.
Send type, size, length, grade and quantity to sales@amardeepsteel.com or call 022-67439130.
Frequently Asked Questions – Monel K500 Fasteners
What is Monel K500?
Monel K-500 (UNS N05500, W.Nr. 2.4375) is a nickel-copper alloy with about 2.3–3.15% aluminium and 0.35–0.85% titanium. It is age-hardened to much higher strength than Monel 400 while keeping similar corrosion resistance in seawater.
Which ASTM standard covers Monel K500 bolts and nuts?
Monel K-500 bolts, screws and studs are covered by ASTM F468 Grade 500 (marking F 468W) and nuts by ASTM F467. ASTM B865 covers the K-500 bar and rod used to make them, not the fasteners themselves.
What is the strength of Monel K500 bolts?
Under ASTM F468, K-500 bolts from 1/4 to 7/8 inch must have 130–180 ksi full-size tensile strength, at least 90 ksi yield, 24–37 HRC hardness and at least 20% elongation.
Is Monel K500 stronger than Monel 400?
Yes. Age-hardened K-500 has roughly twice the tensile strength and more than twice the yield strength of Monel 400 fasteners (90 ksi vs 40 ksi minimum yield under F468).
Is Monel K500 magnetic?
No. Monel K-500 is non-magnetic down to about −100 °C, unlike Monel 400, which is slightly magnetic at room temperature.
Can Monel K500 fasteners be welded?
Welding is not recommended. Heat from welding over-ages or anneals the alloy and lowers the strength gained by age hardening.
Global Reach
ASC LLP supplies nickel-alloy fasteners, pipes, fittings and flanges to offshore, marine, chemical and power customers worldwide, with prompt delivery and full documentation. Buyers in the USA, Europe, the Middle East and Asia rely on our Monel K500 fasteners for certified material and traceability.
Countries We Export To
UNITED STATES, EUROPE, UK, UAE, SAUDI ARABIA, OMAN, KUWAIT, JORDAN, QATAR, INDONESIA, MALAYSIA, BRAZIL, SPAIN, ITALY, FRANCE, GERMANY, BAHRAIN, SRI LANKA, AZERBAIJAN, AUSTRALIA, AUSTRIA, PHILIPPINES, TURKEY, RUSSIA, IRAN, IRAQ, CANADA, KOREA, JAPAN, YEMEN, FINLAND, ZIMBABWE, HUNGARY, PORTUGAL, VIETNAM, MOROCCO, THAILAND, SOUTH AFRICA, MEXICO, SINGAPORE, GREECE, KUWAIT, POLAND, NEW ZEALAND, SWEDEN, SWITZERLAND, BELGIUM, BHUTAN, BANGLADESH, TAIWAN, ROMANIA, CAMBODIA, KAZAKHSTAN, AFGHANISTAN.
