1. Basic Information
- Grade: Monel K500 (Alloy K500)
- UNS: N05500
- W.Nr.: 2.4375
- Alloy Type: Precipitation-hardenable nickel‑copper (Ni‑Cu) austenitic alloy
- Key Characteristics:
- Corrosion resistance equivalent to Monel 400
- Significantly higher strength & hardness via age hardening
- Excellent performance in seawater & sour gas environments
- Non‑magnetic at temperatures down to -101°C
- Low magnetic permeability
2. Chemical Composition (wt%, typical)
| Element | Min | Max |
|---|---|---|
| Nickel (Ni) | 63.0 | 70.0 |
| Copper (Cu) | 27.0 | 33.0 |
| Aluminum (Al) | 2.3 | 3.15 |
| Titanium (Ti) | 0.35 | 0.85 |
| Iron (Fe) | — | 2.0 |
| Manganese (Mn) | — | 1.5 |
| Silicon (Si) | — | 0.5 |
| Carbon (C) | — | 0.25 |
| Sulfur (S) | — | 0.01 |
3. Mechanical Properties (Room Temperature)
Annealed Condition
- Tensile Strength: 550–760 MPa
- Yield Strength (0.2% offset): 240–415 MPa
- Elongation: ≥ 30%
- Hardness: ≤ HRC 22 / HB ≤ 240
Annealed + Age Hardened (Standard)
- Tensile Strength: 950–1050 MPa
- Yield Strength: 690–790 MPa
- Elongation: ≥ 20%
- Hardness: HRC 27–37 / HB 280–350
Spring Temper + Aged
- Tensile Strength: 1100–1380 MPa
- Yield Strength: 900–1170 MPa
- Elongation: ≥ 12%
- Hardness: HRC 38–44
- Modulus of Elasticity: ~205 GPa
- Modulus of Rigidity: ~65.5 GPa
4. Corrosion Resistance
- Excellent resistance to seawater, brackish water, and marine atmospheres
- Outstanding performance in sour gas environments (NACE MR0175 / ISO 15156 compliant)
- Resistant to hydrofluoric acid (HF), sulfuric acid (H₂SO₄), and alkaline solutions
- Low corrosion rates in high‑velocity seawater
- Resistant to chloride‑induced stress corrosion cracking (SCC)
- Similar corrosion performance to Monel 400, with superior mechanical strength
5. Physical Properties
- Density: 8.44 g/cm³
- Melting Range: 1315–1350 °C
- Thermal Expansion (20–100°C): 13.7 × 10⁻⁶ /°C
- Thermal Conductivity (20°C): ~17.5 W/(m·K)
- Electrical Resistivity (20°C): ~0.615 μΩ·m
- Curie Temperature: -65 °C
- Magnetic Permeability (20°C): < 1.005
6. Fabrication & Heat Treatment
- Heat Treatment:
- Solution Anneal: 980–1040°C, rapid cooling (water quench)
- Age Hardening: 480–540°C for 4–16 hours (air cool)
- Welding:
- Good weldability. Recommended filler: ERNiCu‑7
- Post‑weld aging recommended to restore full strength
- Formability:
- Good cold formability in annealed condition
- Moderate work hardening; intermediate annealing may be required
7. Standards & Specifications
- ASTM: B865 (bar/rod), B564 (forgings), B127 (sheet/plate)
- ASME: SB865, SB564, SB127
- NACE: MR0175 / ISO 15156‑3 (sour service)
- QQ‑N‑286, BS 3075/3076 (NA18)
8. Typical Applications
- Marine: Propeller shafts, pump shafts, valves, fasteners, seawater handling equipment
- Oil & Gas: Downhole tools, wellhead components, sour gas production equipment
- Aerospace: Fasteners, springs, structural components
- Chemical Processing: Valves, pumps, heat exchangers, reaction vessels
- Industrial: Springs, fasteners, instrumentation parts, corrosion‑resistant shafts
9. Short Description (for Post List Excerpt)
Monel K500 (UNS N05500)
A precipitation‑hardenable nickel‑copper alloy offering Monel 400‑level corrosion resistance plus significantly higher strength and hardness.
Ideal for marine, oil & gas, and chemical processing applications requiring high performance in corrosive, high‑stress environments.