UNS C94500 Medium Bronze
C94500 bronze is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. C94500 is the UNS number for this material. Additionally, the common industry name is 73-7-20.
It has the lowest tensile strength among cast bronzes. In addition, it has a very low heat capacity and a very low melting temperature.
The graph bars on the material properties cards below compare C94500 bronze to: cast 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
Brinell Hardness
50
Elastic (Young's, Tensile) Modulus
92 GPa 13 x 106 psi
Elongation at Break
12 %
Poisson's Ratio
0.36
Shear Modulus
34 GPa 4.9 x 106 psi
Tensile Strength: Ultimate (UTS)
170 MPa 25 x 103 psi
Tensile Strength: Yield (Proof)
83 MPa 12 x 103 psi
Thermal Properties
Latent Heat of Fusion
160 J/g
Maximum Temperature: Mechanical
130 °C 260 °F
Melting Completion (Liquidus)
940 °C 1730 °F
Melting Onset (Solidus)
800 °C 1480 °F
Specific Heat Capacity
330 J/kg-K 0.078 BTU/lb-°F
Thermal Conductivity
52 W/m-K 30 BTU/h-ft-°F
Thermal Expansion
20 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
10 % IACS
Electrical Conductivity: Equal Weight (Specific)
9.7 % IACS
Otherwise Unclassified Properties
Base Metal Price
30 % relative
Density
9.3 g/cm3 580 lb/ft3
Embodied Carbon
3.2 kg CO2/kg material
Embodied Energy
51 MJ/kg 22 x 103 BTU/lb
Embodied Water
380 L/kg 46 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
17 MJ/m3
Resilience: Unit (Modulus of Resilience)
37 kJ/m3
Stiffness to Weight: Axial
5.5 points
Stiffness to Weight: Bending
16 points
Strength to Weight: Axial
5.2 points
Strength to Weight: Bending
7.4 points
Thermal Diffusivity
17 mm2/s
Thermal Shock Resistance
6.7 points
Alloy Composition
Among cast copper alloys, the composition of C94500 bronze is notable for containing a comparatively high amount of lead (Pb). Lead is used to improve machinability and bearing properties, at the cost of toxicity. It also adds pressure tightness to castings.
| Cu | 66.7 to 78 | |
| Pb | 16 to 22 | |
| Sn | 6.0 to 8.0 | |
| Zn | 0 to 1.2 | |
| Ni | 0 to 1.0 | |
| Sb | 0 to 0.8 | |
| Fe | 0 to 0.15 | |
| S | 0 to 0.080 | |
| P | 0 to 0.050 | |
| Si | 0 to 0.0050 | |
| Al | 0 to 0.0050 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B66: Standard Specification for Bronze Castings for Steam Locomotive Wearing Parts
ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001