Material Family

Nickel-Copper Alloy (Solid-Solution Strengthened)

The classic nickel-copper alloy with a unique performance profile.

Common Designations

UNS N04400, Monel 400, W.Nr. 2.4360, 2.4361, NCu30 (China)

A globally recognized standard. "Monel" is a trademark of Special Metals Corporation.

Chemical Composition (Typical wt.%)

Ni: ≥ 63.0 (Balance)
Cu: 28.0 - 34.0
Fe: 2.5 max
Mn: 2.0 max
C: ≤ 0.30
Si: ≤ 0.50

The high nickel-copper ratio is the source of its unique corrosion resistance, particularly in reducing environments and seawater.

Mechanical Properties (Annealed Plate, Room Temp)

Tensile Strength (Rm): 480 - 620 MPa
Yield Strength (Rp0.2): 170 - 345 MPa
Elongation (A): 35 - 50%

Offers good strength and excellent ductility, making it very tough and forgiving in service.

Physical Properties

Density: 8.80 g/cm³
Melting Range: 1300 - 1350 °C
Useful Service Range: Cryogenic to about 540°C (1000°F).

Maintains good mechanical properties across this entire range.

Key Corrosion Resistance Attributes

• Excellent resistance to seawater and fast-flowing brackish water, resisting cavitation erosion and biofouling.
• Excellent resistance to hydrofluoric acid (HF) at all concentrations and temperatures, especially in the absence of air.• Good resistance to sulfuric (H₂SO₄) and hydrochloric (HCl) acids under reducing conditions.• Good resistance to alkalis, salts, and organic acids.

• ⚠️ Poor resistance to oxidizing acids (e.g., nitric acid, HNO₃) and aerated solutions with oxidants.

A specialist alloy for seawater and specific acid services, especially hydrofluoric acid.

Key Standards (Plate)

ASTM B127 / ASME SB-127 (Primary plate spec for Nickel-Copper Alloy Plate, Sheet, and Strip), DIN 2.4360

ASTM B127 is the main procurement standard.

Fabrication Note

Can be readily welded and fabricated using techniques similar to nickel alloys. However, its high copper content requires attention to heat input to prevent hot cracking.

Widely used in welded marine structures.

Typical Applications

• Marine Engineering: Pump shafts, propeller shafts, seawater valve trim, fasteners, hull sheathing.
• Chemical Processing: Equipment for HF alkylation, HF production, and handling.
• Oil & Gas: Well blowout preventer parts, umbilical cables, seawater cooling systems.
• Power Plants: Feedwater heaters, condenser tubes.
• Desalination Plants: Heat exchanger tubes and vessels.

The historic and premier material for critical seawater-exposed components and HF service.