1.Basic Information
| Item | Details |
|---|---|
| Alloy Grade | Monel 400 |
| UNS Number | N04400 |
| European Norm | W.Nr. 2.4360, 2.4361 |
| Chinese Standard | NS331 |
| Alloy Type | Nickel-Copper (Ni-Cu) Solid Solution Strengthened Corrosion-Resistant Alloy |
| Key Feature | Excellent resistance to seawater, brine, and acidic/alkaline environments, with high mechanical strength and good formability |
2. Chemical Composition (ASTM B127 / ASTM B164 Standard, wt%)
| Element | Min. | Max. |
|---|---|---|
| Nickel (Ni) (incl. Co) | 63.0% | 70.0% |
| Copper (Cu) | 28.0% | 34.0% |
| Iron (Fe) | – | 2.5% |
| Manganese (Mn) | – | 2.0% |
| Carbon (C) | – | 0.3% |
| Silicon (Si) | – | 0.5% |
| Sulfur (S) | – | 0.024% |
3.Mechanical Properties (Annealed Condition, Room Temperature)
| Property | Typical Value | ASTM B164 Requirement |
|---|---|---|
| Ultimate Tensile Strength (UTS) | ≥ 550 MPa (80 ksi) | ≥ 485 MPa (70 ksi) |
| Yield Strength (0.2% Offset) | ≥ 240 MPa (35 ksi) | ≥ 170 MPa (25 ksi) |
| Elongation (in 50mm) | ≥ 45% | ≥ 35% |
| Hardness (Brinell, HB) | 110 ~ 150 | ≤ 180 |
| Modulus of Elasticity | 179 GPa (26×10⁶ psi) | – |
4. Corrosion Resistance (Core Selling Points)
Seawater & Brine Resistance: Outstanding resistance to seawater corrosion at all temperatures up to boiling point, with excellent resistance to pitting and crevice corrosion. Superior to 316L stainless steel in marine environments. Acid & Alkali Resistance: Resistant to sulfuric, hydrochloric, hydrofluoric, and organic acids. Excellent performance in alkaline solutions (sodium hydroxide, caustic soda). Chloride Stress Corrosion Cracking (SCC) Resistance: Immunity to chloride-induced SCC, ideal for marine and offshore applications. Hydrofluoric Acid Resistance: One of the few alloys resistant to anhydrous hydrofluoric acid and hydrogen fluoride gas. Atmospheric Corrosion: Resistant to atmospheric corrosion in industrial and marine environments, with a stable, protective oxide film.
5. Physical Properties
| Property | Typical Value |
|---|---|
| Density | 8.80 g/cm³ (0.317 lb/in³) |
| Melting Range | 1300~1350°C (2372~2462°F) |
| Coefficient of Thermal Expansion (20~100°C) | 13.9×10⁻⁶ /°C (7.7×10⁻⁶ /°F) |
| Thermal Conductivity (20°C) | 21.8 W/(m·K) |
| Specific Heat Capacity (20°C) | 427 J/(kg·K) |
| Magnetic Property | Slightly magnetic (low permeability) |
6. Fabrication & Welding
Heat Treatment: Solution annealing at 870~900°C (1600~1650°F), followed by rapid air cooling or water quenching to ensure optimal corrosion resistance and mechanical properties. Welding: Compatible with TIG, MIG, SMAW, and SAW processes. Recommended filler wire: ERNiCu-7. No post-weld heat treatment required for corrosion resistance. Cold Working: Excellent formability for cold bending, stamping, and deep drawing, with moderate work hardening rate. Hot Working: Hot forging and hot rolling at 900~1150°C (1650~2100°F), followed by solution annealing. Machining: Similar to austenitic stainless steel, use carbide tools with moderate speed and high feed.
7. Typical Applications
Marine: Seawater piping, heat exchangers, propeller shafts, marine hardware Chemical processing: Hydrofluoric acid reactors, alkylation units, caustic soda equipment Oil & gas: Downhole tubing, sour gas production equipment Aerospace: Aircraft fuel and hydraulic line components Power generation: Condenser tubes, desalination equipment Mining: Acid leaching tanks, mining equipment
8. Concise Version (For Post List Excerpt, Ready-to-Use)
Monel 400 (UNS N04400)
A nickel-copper solid solution alloy with 63-70% Ni and 28-34% Cu, offering exceptional resistance to seawater, hydrofluoric acid, and chloride stress corrosion cracking.
High mechanical strength, excellent formability and weldability, ideal for marine, chemical, and oil & gas applications.Annealed condition: UTS ≥ 485MPa, elongation ≥ 35%, suitable for long-term service in harsh corrosive environments.