UNS C64800 Cobalt-Silicon Bronze
C64800 bronze is a bronze formulated for primary forming into wrought products. Cited properties are appropriate for the H04 (full hard) temper. It has the highest electrical conductivity among wrought bronzes. In addition, it has the highest thermal conductivity and a moderately high base cost.
The graph bars on the material properties cards below compare C64800 bronze to: wrought bronzes (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
Elongation at Break
8.0 %
Poisson's Ratio
0.34
Shear Modulus
44 GPa 6.4 x 106 psi
Shear Strength
380 MPa 55 x 103 psi
Tensile Strength: Ultimate (UTS)
640 MPa 94 x 103 psi
Tensile Strength: Yield (Proof)
630 MPa 91 x 103 psi
Thermal Properties
Latent Heat of Fusion
220 J/g
Maximum Temperature: Mechanical
200 °C 390 °F
Melting Completion (Liquidus)
1090 °C 1990 °F
Melting Onset (Solidus)
1030 °C 1890 °F
Specific Heat Capacity
390 J/kg-K 0.093 BTU/lb-°F
Thermal Conductivity
260 W/m-K 150 BTU/h-ft-°F
Thermal Expansion
17 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
65 % IACS
Electrical Conductivity: Equal Weight (Specific)
66 % IACS
Otherwise Unclassified Properties
Base Metal Price
33 % relative
Density
8.9 g/cm3 550 lb/ft3
Embodied Carbon
2.7 kg CO2/kg material
Embodied Energy
43 MJ/kg 18 x 103 BTU/lb
Embodied Water
310 L/kg 37 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
51 MJ/m3
Resilience: Unit (Modulus of Resilience)
1680 kJ/m3
Stiffness to Weight: Axial
7.4 points
Stiffness to Weight: Bending
18 points
Strength to Weight: Axial
20 points
Strength to Weight: Bending
19 points
Thermal Diffusivity
75 mm2/s
Thermal Shock Resistance
23 points
Alloy Composition
Among wrought copper alloys, the composition of C64800 bronze is notable for including chromium (Cr) and cobalt (Co). Chromium additions permits certain types of heat treatment to improve mechanical strength. Cobalt is used to improve strength.
| Cu | 92.4 to 98.8 | |
| Co | 1.0 to 3.0 | |
| Si | 0.2 to 1.0 | |
| Fe | 0 to 1.0 | |
| P | 0 to 0.5 | |
| Ni | 0 to 0.5 | |
| Sn | 0 to 0.5 | |
| Zn | 0 to 0.5 | |
| Cr | 0 to 0.090 | |
| Pb | 0 to 0.050 | |
| res. | 0 to 0.5 |
All values are % weight. Ranges represent what is permitted under applicable standards.