UNS C93500 (Alloy 3C) Leaded Tin Bronze
C93500 bronze is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. C93500 is the UNS number for this material. Additionally, the common industry name is 85-5-9-1. Older literature may refer to this material as ASTM Alloy 3C, but this is now discouraged.
It has a fairly high electrical conductivity among cast bronzes. In addition, it has a fairly low tensile strength and a moderately low embodied energy.
The graph bars on the material properties cards below compare C93500 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
Elastic (Young's, Tensile) Modulus
100 GPa 15 x 106 psi
Elongation at Break
15 %
Poisson's Ratio
0.35
Shear Modulus
38 GPa 5.5 x 106 psi
Tensile Strength: Ultimate (UTS)
220 MPa 32 x 103 psi
Tensile Strength: Yield (Proof)
110 MPa 16 x 103 psi
Thermal Properties
Latent Heat of Fusion
180 J/g
Maximum Temperature: Mechanical
160 °C 320 °F
Melting Completion (Liquidus)
1000 °C 1830 °F
Melting Onset (Solidus)
850 °C 1570 °F
Specific Heat Capacity
360 J/kg-K 0.085 BTU/lb-°F
Thermal Conductivity
70 W/m-K 40 BTU/h-ft-°F
Thermal Expansion
18 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
15 % IACS
Electrical Conductivity: Equal Weight (Specific)
15 % IACS
Otherwise Unclassified Properties
Base Metal Price
31 % relative
Density
9.0 g/cm3 560 lb/ft3
Embodied Carbon
3.0 kg CO2/kg material
Embodied Energy
49 MJ/kg 21 x 103 BTU/lb
Embodied Water
350 L/kg 42 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
28 MJ/m3
Resilience: Unit (Modulus of Resilience)
59 kJ/m3
Stiffness to Weight: Axial
6.3 points
Stiffness to Weight: Bending
17 points
Strength to Weight: Axial
6.9 points
Strength to Weight: Bending
9.1 points
Thermal Diffusivity
22 mm2/s
Thermal Shock Resistance
8.5 points
Alloy Composition
Among cast copper alloys, the composition of C93500 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 | 83 to 86 | |
| Pb | 8.0 to 10 | |
| Sn | 4.3 to 6.0 | |
| Zn | 0 to 2.0 | |
| P | 0 to 1.5 | |
| Ni | 0 to 1.0 | |
| Sb | 0 to 0.3 | |
| Fe | 0 to 0.2 | |
| S | 0 to 0.080 | |
| Si | 0 to 0.0050 | |
| Al | 0 to 0.0050 | |
| res. | 0 to 1.0 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B271: Standard Specification for Copper-Base Alloy Centrifugal Castings
ASTM B505: Standard Specification for Copper Alloy Continuous Castings
ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001