Nickel-Copper (Monel) Alloys

Typical Composition in Percentage:

Alloy 400:


Ni              63 min (Ni + Co)             Cu              28 - 34

Fe                  2.5                            Mn                0.20

C                    0.3                           Si                  0.5

S                   0.024

A nickel-copper alloy with high strength and excellent corrosion resistance in a range of media, including seawater, hydrofluoric acid, sulfuric acid, and alkalies. Used for marine engineering, chemical and hydrocarbon processing equipment, valves, pumps, shafts, fittings, fasteners, and heat exchangers.

Alloy 401:

Ni              40 - 45 (Ni + Co)           Cu                 bal

Fe                 0.75                          Mn                2.25

C                  0.10                          Si                 0.25

S                 0.015

A copper-nickel alloy designed for specialized electrical and electronic applications. It has a very low temperature coefficient of resistance and medium-range electrical resistivity. Used for wire-wound precision resistors and bimetal contacts.

Alloy R-405:

Ni              63 min (Ni + Co)            Cu                28 - 34

Fe                  2.5                           Mn                   2

C                   0.3                            Si                  0.5

S               0.025 - 0.060

The free-machining version of Alloy 400. A controlled amount of sulfur is added to the alloy to provide sulfide inclusions that act as chip breakers during machining. Used for meter and valve parts, fasteners, and screw machine products.

Alloy 450:


Ni               29 - 33                             Cu               bal

Fe              0.4 - 1                              Mn                1

S                0.02                                Zn                 1

Pb               0.05                                P                 0.02

A copper-nickel alloy of the 70-30 type having superior weldability. It is resistant to corrosion and biofouling in seawater, has good fatigue strength, and has relatively high thermal conductivity. Used for seawater condensers, condenser plates, distiller tubes, evaporator and heat exchanger tubes, and saltwater piping.

Alloy K-500:

Ni               63 min (Ni + Co)               Cu                  27 - 33

Fe                      2                               Mn                    1.5

C                     0.25                            Si                     0.5

S                     0.01                            Al                  2.3 - 3.15

Ti                0.35 - 0.85

A precipitation-hardenable nickel-copper alloy that combines the corrosion resistance of Alloy 400 with greater strength and hardness. It also has low permeability and is nonmagnetic to under -100 oC (-150 oF). Used for pump shafts, oil well tools and instruments, doctor blades and scrapers, springs, valve trim, fasteners, and marine propeller shafts.

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