UNS C93800 (Alloy 3D, SAE 67) Hard Bronze
C93800 bronze is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. 67 is the SAE designation for this material. C93800 is the UNS number. Additionally, the common industry name is 78-7-15. Older literature may refer to this material as ASTM Alloy 3D, but this is now discouraged.
It has a very low heat capacity among cast bronzes. In addition, it has a very low tensile strength and a moderately low ductility.
The graph bars on the material properties cards below compare C93800 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
96 GPa 14 x 106 psi
Elongation at Break
9.7 %
Poisson's Ratio
0.35
Shear Modulus
35 GPa 5.1 x 106 psi
Tensile Strength: Ultimate (UTS)
200 MPa 29 x 103 psi
Tensile Strength: Yield (Proof)
120 MPa 17 x 103 psi
Thermal Properties
Latent Heat of Fusion
170 J/g
Maximum Temperature: Mechanical
140 °C 280 °F
Melting Completion (Liquidus)
940 °C 1730 °F
Melting Onset (Solidus)
850 °C 1570 °F
Specific Heat Capacity
340 J/kg-K 0.081 BTU/lb-°F
Thermal Conductivity
52 W/m-K 30 BTU/h-ft-°F
Thermal Expansion
19 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
11 % IACS
Electrical Conductivity: Equal Weight (Specific)
11 % IACS
Otherwise Unclassified Properties
Base Metal Price
31 % relative
Density
9.1 g/cm3 570 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 45 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
17 MJ/m3
Resilience: Unit (Modulus of Resilience)
70 kJ/m3
Stiffness to Weight: Axial
5.9 points
Stiffness to Weight: Bending
17 points
Strength to Weight: Axial
6.1 points
Strength to Weight: Bending
8.4 points
Thermal Diffusivity
17 mm2/s
Thermal Shock Resistance
8.1 points
Alloy Composition
Among cast copper alloys, the composition of C93800 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 | 75 to 79 | |
| Pb | 13 to 16 | |
| Sn | 6.3 to 7.5 | |
| P | 0 to 1.5 | |
| Ni | 0 to 1.0 | |
| Zn | 0 to 0.8 | |
| Sb | 0 to 0.8 | |
| Fe | 0 to 0.15 | |
| 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