2.4375 (Monel K500 / UNS N05500) is a precipitation-hardened nickel-copper alloy round bar. Compared with conventional Monel 400, K500 adds aluminum and titanium elements, achieving age hardening heat treatment to obtain much higher tensile strength and yield strength while retaining excellent corrosion resistance. It provides outstanding resistance to seawater, marine atmosphere, brine, alkaline and non-oxidizing acid media. With excellent mechanical properties, low magnetic permeability, high fatigue resistance and good wear resistance, 2.4375 round bar is widely used for marine, offshore, oil & gas, chemical and high-precision mechanical components.

2. International Equivalent Grade (Cross Standard)

Germany / European Standard: W.Nr 2.4375, EN NiCu30Fe

USA Standard: UNS N05500, Monel K500, ASTM B865 / QQ-N-286

British Standard: BS 3076 NA18

Chinese Standard: GB N05500 / NCu30-4-2

Japanese Standard: JIS NW4400 equivalent special alloy

3. W.Nr 2.4375 / Monel K500 Chemical Composition (Weight % / ASTM B865 Standard)

Strict controlled Al & Ti ratio ensures stable aging hardening effect and consistent mechanical strength.

Nickel (Ni + Co): 63.0 – 70.0%

Copper (Cu): 27.0 – 33.0%

Aluminum (Al): 2.30 – 3.15%

Titanium (Ti): 0.35 – 0.85%

Iron (Fe): ≤ 2.00%

Manganese (Mn): ≤ 1.50%

Silicon (Si): ≤ 0.50%

Carbon (C): ≤ 0.25%

Sulfur (S): ≤ 0.010%

Phosphorus (P): ≤ 0.015%

Others: Balance

4. Physical Properties

Density: 8.44 g/cm³

Melting Range: 1300 – 1350°C

Modulus of Elasticity: 179 GPa

Thermal Conductivity: 18.5 W/m·K

Thermal Expansion Coefficient: 14.0 × 10⁻⁶ /°C

Electrical Resistivity: 0.52 μΩ·m

Magnetic Property: Very low magnetic permeability (non-magnetic in most working conditions)

Max Service Temperature: Up to 650°C

5. Mechanical Properties (Standard Condition)

5.1 Solution Annealed + Age Hardened (Main Delivery State)

Tensile Strength: ≥ 965 MPa

0.2% Yield Strength: ≥ 690 MPa

Elongation (50mm): ≥ 20%

Hardness: ≤ 41 HRC

5.2 Cold Drawn & Stress Relieved

Tensile Strength: ≥ 1050 MPa

Yield Strength: ≥ 850 MPa

Elongation: ≥ 15%

Feature: Much higher strength than Monel 400, excellent fatigue resistance and wear resistance under dynamic load.

6. Surface Finishes & Dimensions Tolerance

6.1 Common Surface Types

Black Hot Rolled Surface: Original hot rolled oxide surface, for forging, rough machining and structural parts

Pickled Matte Surface: Uniform silver-gray clean surface, no oxide scale, standard industrial finish

Cold Drawn Bright Surface: Smooth bright surface, precise diameter, direct machining available

Precision Ground Surface: High mirror smoothness, tight tolerance, for precision shaft and valve parts

6.2 Diameter Tolerance Classification

Hot Rolled Bar: ±0.3 ~ ±0.8 mm

Cold Drawn Bar: ±0.05 ~ ±0.15 mm

Precision Ground Bar: h8 / h9 / h10 tolerance (±0.01~0.03 mm)

6.3 Size Range

Round bar diameter: Φ3mm – Φ300mm

Standard length: 3000mm / 6000mm / custom fixed length

7. Core Product Advantages

Ultra-high Strength: Age-hardening strengthened, strength nearly 2 times higher than Monel 400

Superior Marine Corrosion Resistance: Excellent resistance to seawater corrosion, chloride stress corrosion, brine and salt spray

Good Acid & Alkali Resistance: Stable performance in sulfuric acid, hydrofluoric acid, alkaline solution and reducing medium

Low Magnetic Property: Non-magnetic, suitable for magnetic-sensitive equipment

Excellent Fatigue & Wear Resistance: Ideal for high-speed rotating shafts and reciprocating mechanical parts

Good Weldability & Machinability: Stable structure after heat treatment, suitable for cutting, turning, drilling and welding

High Temperature Stability: Maintains stable mechanical properties under 650°C working environment

8. Main Applications

Marine & Offshore Industry: Ship shafting, propeller shafts, seawater pump shafts, valve stems, offshore platform fasteners

Oil & Gas Industry: Downhole tools, wellhead parts, high-pressure corrosion-resistant bolts and connectors

Chemical Industry: Hydrofluoric acid equipment, acid-resistant pumps, heat exchanger parts, reactor components

Desalination & Water Treatment: Seawater desalination equipment, brine circulation system parts

Precision Machinery: High-strength wear-resistant shafts, instrument parts, hydraulic valve cores

Aerospace & Energy: Low-magnetic structural parts, high-temperature corrosion-resistant fasteners

9. Production & Testing Standard

Executive Standards: ASTM B865, QQ-N-286, DIN 17743, EN 10263

Full inspection: Spectrum chemical analysis, mechanical tensile & hardness test, ultrasonic flaw detection, dimensional tolerance inspection, surface defect inspection

10. Export Packaging

Bundled with steel strips, wrapped with waterproof film and woven bag, end protected by plastic caps. Anti-rust oil applied for long sea transportation. Custom label and packaging available.