Monel Alloys
Monel 400 (UNS N04400) — Composition, Properties & Supply
Monel 400 (UNS N04400) is a solid-solution nickel-copper alloy (Ni ≥ 63%, Cu 28–34%) with excellent resistance to seawater, hydrofluoric acid, sulphuric acid and alkalis, plus higher strength than pure nickel. It is a classic material for marine engineering, pump shafts and valves.
What is the chemical composition of Monel 400?
| Element | Symbol | Content (wt%) |
|---|---|---|
| Ni | Ni | ≥ 63.0 |
| Cu | Cu | 28.0–34.0 |
| Fe | Fe | ≤ 2.5 |
| Mn | Mn | ≤ 2.00 |
| C | C | ≤ 0.30 |
| Si | Si | ≤ 0.50 |
| S | S | ≤ 0.024 |
Values are typical specification limits. Actual heat analysis is reported on the EN 10204 3.1 mill test certificate supplied with each shipment.
What are the mechanical properties of Monel 400?
| Property | Value | Note |
|---|---|---|
| Tensile strength | ≥ 480 MPa | Room temperature |
| Yield strength (0.2% offset) | ≥ 195 MPa | Room temperature |
| Elongation | ≥ 35 % | Gauge length 50 mm / 4D |
| Hardness | ≤ 170 HB | Brinell / Rockwell |
What are the physical properties of Monel 400?
| Property | Value |
|---|---|
| Density | 8.80 g/cm³ |
| Melting range | 1300–1350 °C |
| Thermal conductivity | 21.8 W/m·K |
| Elastic modulus | 179 GPa |
| Maximum service temperature | 600 °C |
What are the key characteristics of Monel 400?
- Resists seawater, salt spray and high-velocity impingement
- Material of choice for anhydrous hydrofluoric acid
- Resists alkalis including molten caustic, and many organic acids
- Tough down to −100 °C
- Higher thermal conductivity than most nickel alloys
Where is Monel 400 used?
- Marine and desalination piping, pump shafts and propellers
- HF acid production, storage and transfer equipment
- Crude distillation overhead condensing systems
- Valves, pump bodies and fasteners
- Musical instrument strings and architectural roofing
Which standards and specifications cover Monel 400?
What product forms are available?
Frequently asked questions
What is the difference between Monel 400 and Monel K-500?
K-500 adds 2.3–3.15% aluminium and 0.35–0.85% titanium to the 400 chemistry and is strengthened by γ′ ageing, giving two to three times the yield strength of 400 (around 690 MPa) and much higher hardness. However, K-500 is slightly less corrosion resistant than 400 in some acids and its aged condition needs care regarding stress-corrosion susceptibility.
How well does Monel 400 resist seawater?
Very well. In flowing seawater the corrosion rate is typically below 0.025 mm/a and it resists cavitation and impingement, which is why it has long been used for pump shafts, propeller shafts and heat exchangers. In stagnant seawater or where sulphide contamination exists, pitting can occur — avoid long stagnation and control sulphides.
Need Monel 400 bar, tube, plate or forgings?
Send the grade, dimensions, standard and quantity. We answer within 10 minutes on working days and quote within 24 hours, with EN 10204 3.1 certification.
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