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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.

Copper (Cu) 79 to 85
Zinc (Zn) 12 to 16
Silicon (Si) 3.0 to 5.0
Aluminum (Al) 0 to 0.5
Lead (Pb) 0 to 0.5
Residuals 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