Properties and Composition of Monel 400

This nickel-copper alloy resists corrosion in most environments

monel alloy
••• Langley Alloys

Monel 400 is a nickel-copper alloy that is resistant to corrosion in many environments. It consists of two crystalline solids that, together, form a single new solid.

Monel was the brainchild of Robert Crooks Stanley of the International Nickel Company. Patented in 1906, it was named for the president of the company, Ambrose Monell (the second "L" was removed from the name of the metal because at that time, it was not possible to patent a person's name).

Overview of Monel 400

Monel alloys are nickel-based alloys that contain between 29 and 34 percent copper. They are valued for their resistance to attack by acids and alkalis, as well as for their high mechanical strength and good ductility. 

Monel 400 contains the same quantity of nickel and copper as is found in a naturally occurring nickel ore in Ontario, Canada. It has high strength and can only be hardened by cold working. Due to its resistance to deterioration, alloy 400 is most often used in parts found in marine and chemical environments.

While it is a very useful metal, it is cost-prohibitive in most applications. Monel 400 costs between five and 10 times as much as ordinary nickel or copper. As a result, it is used rarely -- and only when no other metal could do the same job. As an example, Monel 400 is one of the few alloys that maintains its strength in sub-zero temperatures, so is used in these circumstances.

Standard Composition of Monel 400

Monel alloy 400 is composed of between 28 and 34 percent copper and 63 percent (minimum) nickel. Manganese, iron and silicon are also present in smaller amounts. The following describes the standard composition of Monel 400:

  • Nickel (plus cobalt) - 63 percent minimum
  • Carbon - 0.3 percent maximum
  • Manganese - 2.0 percent maximum
  • Iron - 2.5 percent maximum
  • Sulfur - 0.024 percent maximum.
  • Silicon - 0.5 percent maximum
  • Copper - 28  to 34 percent

Properties of Nickel-Copper Alloy Monel 400

The following table describes the properties of Monel 400. Relative to other similar metals it is unusually strong and corrosion-resistant.

PropertyValue (Metric)Value (Imperial)
Density 8.80*103kg/m3549lb/ft3
Modulus of Elasticity179GPa26000ksi
Thermal Expansion (20ºC)13.9*10-6ºC-17.7*10-6in/(in*ºF)
Specific Heat Capacity427J/(kg*K)0.102BTU/(lb*ºF)
Thermal Conductivity21.8W/(m*K)151BTU*in/(hr*ft2*ºF)
Electric Resistivity54.7*10-8Ohm*m54.7*10-6Ohm*cm
Tensile Strength (annealed)550MPa79800psi
Yield Strength (annealed)240MPa34800psi
Liquidus Temperature1350ºC2460ºF
Solidus Temperature1300ºC2370ºF


SubsTech. Substances & Technology
Special Metals. Monel Alloy.