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What is Monel K-500?
Quick answer
- Definition
- Monel K-500 (Alloy K-500, UNS N05500) is an age-hardenable nickel-copper alloy that adds aluminium and titanium to Alloy 400, giving about three times its yield strength with similar corrosion resistance.
- Family
- Nickel-copper (Ni-Cu) alloy
- Key strength
- Age-hardenable Ni-Cu alloy
- Main forms
- Plates, Sheets, Bars, Bolts, Nuts, Washers
- Typical uses
- Marine pump and propeller shafts; Impellers and valve trim; Oil-well drill collars and tools
Alloy K-500 combines the seawater and chemical resistance of Monel 400 with much higher strength and hardness, gained by precipitating Ni3(Al,Ti) during ageing. It keeps its strength to about 650 °C and is tough at low temperatures.
Most supply is round bar for pump shafts, impellers, propeller shafts, oil-well drill collars and tools, doctor blades, springs and high-strength fasteners in marine and oilfield service. The client term "Monel K500" refers to this alloy.
Key characteristics
- Age-hardenable Ni-Cu alloy
- About 3× the yield strength of Monel 400 when aged
- Seawater resistance similar to Monel 400
- Mainly bar for shafts and fasteners
What are the specifications and equivalents of Monel K-500?
| Product form | Specification / designation | Product page |
|---|---|---|
| Plates | To order | Monel K-500 plates → |
| Sheets | To order | Monel K-500 sheets → |
| Bars | ASTM B865 / ASME SB865 | Monel K-500 bars → |
| Bolts | ASTM B865 bar stock | Monel K-500 bolts → |
| Nuts | ASTM B865 | Monel K-500 nuts → |
| Washers | To order | Monel K-500 washers → |
UNS N05500 · EN 2.4375 (cross-reference; limits are similar but not identical) · Monel® is a trademark of Special Metals Corporation; generic material is supplied to the specification on your order.
Standards: ASTM B865.
What is the chemical composition of Monel K-500?
| Element | Limit (%) |
|---|---|
| Ni | 63.0 min |
| Cu | 27.0 – 33.0 |
| Al | 2.30 – 3.15 |
| Ti | 0.35 – 0.85 |
| Fe | 2.0 max |
| Mn | 1.5 max |
| C | 0.25 max |
| Si | 0.5 max |
What are the mechanical properties of Monel K-500?
| Property | Value |
|---|---|
| Tensile strength | 965 MPa (140 ksi) |
| Yield strength (0.2% offset) | 690 MPa (100 ksi) |
| Elongation | 20% |
| Hardness | ≈ 27 – 35 HRC |
Physical properties and service temperature
| Property | Value |
|---|---|
| Density (typical) | 8.44 g/cm³ (8440 kg/m³) |
| Magnetism | Only slightly magnetic at room temperature. |
| Heat treatment | Supplied annealed or solution annealed, and age-hardened when specified. |
| Service temperature | — |
How is Monel K-500 welded and fabricated?
Weldable by TIG, MIG and SMAW with matching or over-alloyed nickel fillers. Keep surfaces clean of sulphur and low-melting contaminants.
Always follow a qualified welding procedure (for example ASME Section IX) and the filler-metal recommendations for Monel K-500. Verify incoming material by PMI and check the mill test certificate against the specification.
Which Monel K-500 products do we supply?
Monel K-500 is available in 6 product forms, from ready stock or mill-sourced to your specification, with EN 10204 3.1 mill test certificates (3.2 with third-party inspection on request).
Monel K-500 PlatesTo orderSpecification & sizes
How it's madeSlabs are hot-rolled on a reversing plate mill (or a Steckel/hot-strip mill for thinner plate), then heat treated (annealed, normalised, or quenched and tempered, depending on material), descaled and pickled or shot-blasted. Plates are cut to size by plasma, oxy-fuel, waterjet or shearing.
- Specification
- To order
- Size range
- Thickness about 3 – 150 mm (and heavier on request), widths 1,000 – 3,000 mm, lengths 2,000 – 12,000 mm; cut-to-size and profile-cut parts
- Finish
- No.1 (hot-rolled, annealed and pickled) for stainless; shot-blasted, mill scale or primed for carbon steel
- Ends
- Mill edge, sheared, plasma or waterjet cut, profile cut to drawing
Testing & documents
- Chemical analysis and tensile tests (per plate or heat)
- Impact tests for low-temperature and pressure-vessel plates
- Ultrasonic testing (e.g. ASTM A435 / A578) when specified
- IGC, HIC and simulated PWHT tests as required
- Flatness and dimensional inspection
- EN 10204 3.1 certificate; 3.2 with third-party inspection
Monel K-500 SheetsTo orderSpecification & sizes
How it's madeHot-rolled coil is cold-rolled to final thickness, then annealed and pickled (2B/2D) or bright annealed (BA), temper-passed, and polished or textured as needed. Coils are then levelled and cut into sheets.
- Specification
- To order
- Size range
- Thickness about 0.3 – 6 mm, standard sizes 1,000 × 2,000, 1,219 × 2,438 (4 × 8 ft), 1,250 × 2,500 and 1,500 × 3,000 mm; custom cut lengths
- Finish
- 2B, 2D, BA, No.4 (brushed), HL (hairline), No.8 (mirror), embossed, PVC or laser-film protected
- Ends
- Sheared or slit edges; laser-cut blanks on request
Testing & documents
- Chemical and mechanical tests
- Surface and finish inspection
- Thickness and flatness checks
- Hardness and bend tests as specified
- EN 10204 3.1 certificate; 3.2 with third-party inspection
Monel K-500 BarsASTM B865 / ASME SB865Specification & sizes
How it's madeBillets are hot-rolled or forged to size, then heat treated (annealed, solution treated, or quenched and tempered) and finished by descaling, peeling, turning, cold-drawing or centreless grinding for bright bar with tight tolerance.
- Specification
- ASTM B865 / ASME SB865
- Size range
- Round bars about 3 – 500 mm diameter; hex 6 – 100 mm A/F; square and flat sections to order; lengths 3 – 6 m random or cut to size
- Finish
- Black (hot-rolled), peeled, bright drawn, centreless ground and polished (h9 / h11 tolerance)
- Ends
- Saw-cut, chamfered on request
Testing & documents
- Chemical and mechanical tests
- Ultrasonic testing for internal soundness
- Hardness, IGC and impact tests as specified
- Straightness and tolerance checks
- EN 10204 3.1 certificate; 3.2 with third-party inspection
Monel K-500 BoltsASTM B865 bar stockSpecification & sizes
How it's madeCut from heat-treated bar (or forged and heat treated), then threaded by rolling or cutting, and coated if required.
- Specification
- ASTM B865 bar stock
- Size range
- M6 – M100 and ¼" – 4" (larger on request); lengths to flange tables or drawing
- Finish
- Plain, black oxide, zinc, hot-dip galvanised, PTFE-based fluoropolymer, zinc-nickel
- Ends
- Chamfered points; full or partial thread
Testing & documents
- Chemical and mechanical tests of bar and finished bolts
- Hardness tests
- Proof-load and wedge tests where applicable
- Coating thickness and adhesion
- EN 10204 3.1 certificate; 3.2 with third-party inspection
Monel K-500 NutsASTM B865Specification & sizes
How it's madeHot-forged or cold-formed from bar, heat treated (for hardenable grades), tapped and coated if required.
- Specification
- ASTM B865
- Size range
- M6 – M100 and ¼" – 4"; heavy hex to ASME B18.2.2; metric to ISO 4032 / 4033
- Finish
- Plain, zinc, galvanised (tapped oversize), fluoropolymer
Testing & documents
- Proof-load tests
- Hardness tests
- Chemical analysis
- EN 10204 3.1 certificate; 3.2 with third-party inspection
Monel K-500 WashersTo orderSpecification & sizes
How it's madeStamped or machined from plate or strip and heat treated where required.
- Specification
- To order
- Size range
- M6 – M100 and ¼" – 4" bolt sizes
- Finish
- Plain, zinc, galvanised
Testing & documents
- Hardness tests
- Dimensional checks
- EN 10204 3.1 certificate; 3.2 with third-party inspection
Where is Monel K-500 used?
Typical applications
- Marine pump and propeller shafts
- Impellers and valve trim
- Oil-well drill collars and tools
- High-strength fasteners and springs
- Doctor blades and scrapers
What should you specify when buying Monel K-500?
- Grade and specification, e.g. To order
- Product form, size and tolerance
- Heat treatment / condition and surface finish
- Quantity, delivery location and required date
- Tests: PMI, hydro/NDT, IGC, impact or hardness as required
- Certificate type (EN 10204 3.1 / 3.2) and third-party inspection
See our RFQ checklist guide and what drives metal prices.
Explore more on Monel K-500
Monel K-500 products
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Frequently asked questions
What is the difference between Monel 400 and K-500?
K-500 adds aluminium and titanium, which allows it to be age-hardened to much higher strength and hardness. Corrosion resistance is similar.
Is Monel K500 the same as K-500?
Yes. The trademark styling is "K-500"; "K500" is a common alternative spelling.
What is Monel K-500 used for?
Marine pump and propeller shafts, Impellers and valve trim, Oil-well drill collars and tools, High-strength fasteners and springs. It's used across Marine & Offshore, Shipbuilding, Oil & Gas, Heavy Engineering.
What is the UNS number of Monel K-500?
Monel K-500 is designated UNS N05500; the closest EN cross-reference is 2.4375.
Which product forms is Monel K-500 available in?
Plates, Sheets, Bars, Bolts, Nuts, Washers, to To order, To order, ASTM B865 / ASME SB865 and related specifications.
What is the density of Monel K-500?
About 8.44 g/cm³ (8440 kg/m³), used for weight calculations.
Is Monel K-500 magnetic?
Only slightly magnetic at room temperature.