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UNS C74000 Nickel Silver

C74000 nickel silver is a copper-nickel alloy formulated for primary forming into wrought products. C74000 is the UNS number for this material. Additionally, the common industry name is 70-10-20. Older literature may refer to this material as ASTM Copper-Nickel Type 9, but this is now discouraged.

It has a moderately high electrical conductivity among the wrought copper-nickels in the database.

The properties of C74000 nickel silver include five 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 C74000 nickel silver 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

120 GPa 17 x 106 psi

Poisson's Ratio

0.32

Rockwell B Hardness

70 to 88

Shear Modulus

44 GPa 6.5 x 106 psi

Tensile Strength: Ultimate (UTS)

380 to 590 MPa 55 to 85 x 103 psi

Thermal Properties

Latent Heat of Fusion

200 J/g

Maximum Temperature: Mechanical

180 °C 360 °F

Melting Completion (Liquidus)

990 °C 1820 °F

Melting Onset (Solidus)

950 °C 1730 °F

Specific Heat Capacity

390 J/kg-K 0.094 BTU/lb-°F

Thermal Expansion

18 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

40 % IACS

Electrical Conductivity: Equal Weight (Specific)

42 % IACS

Otherwise Unclassified Properties

Base Metal Price

30 % relative

Density

8.5 g/cm3 530 lb/ft3

Embodied Carbon

3.4 kg CO2/kg material

Embodied Energy

54 MJ/kg 23 x 103 BTU/lb

Embodied Water

310 L/kg 37 gal/lb

Common Calculations

Stiffness to Weight: Axial

7.7 points

Stiffness to Weight: Bending

19 points

Strength to Weight: Axial

13 to 19 points

Strength to Weight: Bending

14 to 18 points

Thermal Shock Resistance

13 to 19 points

Alloy Composition

Among wrought copper alloys, the composition of C74000 nickel silver 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) 69 to 73.5
Zinc (Zn) 14.2 to 22
Nickel (Ni) 9.0 to 11
Manganese (Mn) 0 to 0.5
Iron (Fe) 0 to 0.25
Lead (Pb) 0 to 0.1
Residuals 0 to 0.5

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

Followup Questions

Similar Alloys

Further Reading

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

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015