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UNS C71000 Copper-Nickel

C71000 copper-nickel is a copper-nickel alloy formulated for primary forming into wrought products. C71000 is the UNS number for this material. Additionally, the EN chemical designation is CuNi20. The British Standard (BS) designation is CN104. And the common industry name is Cupronickel 20.

It has a moderately high melting temperature among the wrought copper-nickels in the database.

The properties of C71000 copper-nickel include seven common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare C71000 copper-nickel to: wrought copper-nickels (top), all copper alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

130 GPa 19 x 106 psi

Poisson's Ratio


Rockwell B Hardness

59 to 85

Rockwell Superficial 30T Hardness

56 to 73

Shear Modulus

49 GPa 7.1 x 106 psi

Tensile Strength: Ultimate (UTS)

320 to 560 MPa 47 to 82 x 103 psi

Thermal Properties

Latent Heat of Fusion

230 J/g

Maximum Temperature: Mechanical

240 °C 460 °F

Melting Completion (Liquidus)

1200 °C 2190 °F

Melting Onset (Solidus)

1150 °C 2100 °F

Specific Heat Capacity

400 J/kg-K 0.1 BTU/lb-°F

Thermal Conductivity

43 W/m-K 25 BTU/h-ft-°F

Thermal Expansion

15 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

6.5 % IACS

Electrical Conductivity: Equal Weight (Specific)

6.6 % IACS

Otherwise Unclassified Properties

Base Metal Price

37 % relative


8.9 g/cm3 560 lb/ft3

Embodied Carbon

4.3 kg CO2/kg material

Embodied Energy

63 MJ/kg 27 x 103 BTU/lb

Embodied Water

290 L/kg 35 gal/lb

Common Calculations

Stiffness to Weight: Axial

8.2 points

Stiffness to Weight: Bending

19 points

Strength to Weight: Axial

10 to 18 points

Strength to Weight: Bending

12 to 17 points

Thermal Diffusivity

12 mm2/s

Thermal Shock Resistance

12 to 20 points

Alloy Composition

Among wrought copper alloys, the composition of C71000 copper-nickel is notable for including manganese (Mn) and nickel (Ni). Manganese is used to improve strength without a proportional reduction in ductility. Nickel is used to improve strength (particularly at elevated temperatures) and corrosion resistance.

Copper (Cu)Cu 73.5 to 80.5
Nickel (Ni)Ni 19 to 23
Iron (Fe)Fe 0.5 to 1.0
Manganese (Mn)Mn 0 to 1.0
Zinc (Zn)Zn 0 to 1.0
Lead (Pb)Pb 0 to 0.050
Residualsres. 0 to 0.5

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM B111: Standard Specification for Copper and Copper-Alloy Seamless Condenser Tubes and Ferrule Stock

ASTM B122: Standard Specification for Copper-Nickel-Tin Alloy, Copper-Nickel-Zinc Alloy (Nickel Silver), and Copper-Nickel Alloy Plate, Sheet, Strip, and Rolled Bar

ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001