UNS C79200 (CW404J) Leaded Nickel Silver
C79200 nickel silver is a copper-nickel alloy formulated for primary forming into wrought products. CW404J is the EN numeric designation for this material. C79200 is the UNS number. Additionally, the EN chemical designation is CuNi12Zn25Pb1.
It has a moderately high electrical conductivity and a moderately low melting temperature among wrought copper-nickels.
The properties of C79200 nickel silver include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare C79200 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
Shear Modulus
44 GPa 6.4 x 106 psi
Tensile Strength: Ultimate (UTS)
480 to 540 MPa 70 to 79 x 103 psi
Thermal Properties
Latent Heat of Fusion
190 J/g
Maximum Temperature: Mechanical
170 °C 340 °F
Melting Completion (Liquidus)
950 °C 1750 °F
Melting Onset (Solidus)
910 °C 1660 °F
Specific Heat Capacity
390 J/kg-K 0.093 BTU/lb-°F
Thermal Conductivity
42 W/m-K 24 BTU/h-ft-°F
Thermal Expansion
19 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
28 % IACS
Electrical Conductivity: Equal Weight (Specific)
30 % IACS
Otherwise Unclassified Properties
Base Metal Price
30 % relative
Density
8.4 g/cm3 520 lb/ft3
Embodied Carbon
3.6 kg CO2/kg material
Embodied Energy
56 MJ/kg 24 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
16 to 18 points
Strength to Weight: Bending
16 to 18 points
Thermal Diffusivity
13 mm2/s
Thermal Shock Resistance
16 to 18 points
Alloy Composition
Among wrought copper alloys, the composition of C79200 nickel silver is notable for including manganese (Mn) and containing a comparatively high amount of lead (Pb). Manganese is used to improve strength without a proportional reduction in ductility. Lead is used to improve machinability and bearing properties, at the cost of toxicity.
| Cu | 59 to 66.5 | |
| Zn | 17.9 to 29.2 | |
| Ni | 11 to 13 | |
| Pb | 0.8 to 1.4 | |
| Mn | 0 to 0.5 | |
| Fe | 0 to 0.25 | |
| res. | 0 to 0.5 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B151: Standard Specification for Copper-Nickel-Zinc Alloy (Nickel Silver) and Copper-Nickel Rod and Bar
ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001