UNS C87500 Silicon Brass
C87500 brass is a brass formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. C87500 is the UNS number for this material. Older literature may refer to this material as ASTM Alloy 13B, but this is now discouraged.
It has a moderately low thermal conductivity among cast brasses. In addition, it has a fairly low electrical conductivity and a fairly low embodied energy.
The graph bars on the material properties cards below compare C87500 brass to: cast brasses (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
110 GPa 16 x 106 psi
Elongation at Break
18 %
Poisson's Ratio
0.33
Shear Modulus
42 GPa 6.0 x 106 psi
Tensile Strength: Ultimate (UTS)
460 MPa 67 x 103 psi
Tensile Strength: Yield (Proof)
190 MPa 27 x 103 psi
Thermal Properties
Latent Heat of Fusion
260 J/g
Maximum Temperature: Mechanical
170 °C 340 °F
Melting Completion (Liquidus)
920 °C 1680 °F
Melting Onset (Solidus)
820 °C 1510 °F
Specific Heat Capacity
410 J/kg-K 0.1 BTU/lb-°F
Thermal Conductivity
28 W/m-K 16 BTU/h-ft-°F
Thermal Expansion
18 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
6.7 % IACS
Electrical Conductivity: Equal Weight (Specific)
7.3 % IACS
Otherwise Unclassified Properties
Base Metal Price
27 % relative
Density
8.3 g/cm3 520 lb/ft3
Embodied Carbon
2.7 kg CO2/kg material
Embodied Energy
44 MJ/kg 19 x 103 BTU/lb
Embodied Water
300 L/kg 36 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
67 MJ/m3
Resilience: Unit (Modulus of Resilience)
160 kJ/m3
Stiffness to Weight: Axial
7.4 points
Stiffness to Weight: Bending
19 points
Strength to Weight: Axial
16 points
Strength to Weight: Bending
16 points
Thermal Diffusivity
8.3 mm2/s
Thermal Shock Resistance
17 points
Alloy Composition
Among cast copper alloys, the composition of C87500 brass is notable for containing a comparatively high amount of silicon (Si). Silicon is used to improve casting fluidity and lower melting temperature. It also raises strength at the expense of ductility.
| Cu | 79 to 85 | |
| Zn | 12 to 16 | |
| Si | 3.0 to 5.0 | |
| Al | 0 to 0.5 | |
| Pb | 0 to 0.5 | |
| res. | 0 to 0.5 |
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
ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015