UNS C84800 Leaded Semi-Red Brass
C84800 brass is a brass formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. C84800 is the UNS number for this material. Additionally, the common industry name is 76-2.5-6.5-15. Older literature may refer to this material as ASTM Alloy 5B, but this is now discouraged.
It has a moderately low tensile strength and a moderately low electrical conductivity among cast brasses.
The graph bars on the material properties cards below compare C84800 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
100 GPa 15 x 106 psi
Elongation at Break
18 %
Poisson's Ratio
0.33
Shear Modulus
39 GPa 5.6 x 106 psi
Tensile Strength: Ultimate (UTS)
230 MPa 33 x 103 psi
Tensile Strength: Yield (Proof)
100 MPa 15 x 103 psi
Thermal Properties
Latent Heat of Fusion
180 J/g
Maximum Temperature: Mechanical
150 °C 290 °F
Melting Completion (Liquidus)
950 °C 1750 °F
Melting Onset (Solidus)
830 °C 1530 °F
Specific Heat Capacity
370 J/kg-K 0.088 BTU/lb-°F
Thermal Conductivity
72 W/m-K 42 BTU/h-ft-°F
Thermal Expansion
19 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
16 % IACS
Electrical Conductivity: Equal Weight (Specific)
17 % IACS
Otherwise Unclassified Properties
Base Metal Price
27 % relative
Density
8.6 g/cm3 540 lb/ft3
Embodied Carbon
2.8 kg CO2/kg material
Embodied Energy
46 MJ/kg 20 x 103 BTU/lb
Embodied Water
340 L/kg 40 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
34 MJ/m3
Resilience: Unit (Modulus of Resilience)
53 kJ/m3
Stiffness to Weight: Axial
6.6 points
Stiffness to Weight: Bending
18 points
Strength to Weight: Axial
7.3 points
Strength to Weight: Bending
9.6 points
Thermal Diffusivity
23 mm2/s
Thermal Shock Resistance
8.2 points
Alloy Composition
Among cast copper alloys, the composition of C84800 brass 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 77 | |
| Zn | 13 to 17 | |
| Pb | 5.5 to 7.0 | |
| Sn | 2.0 to 3.0 | |
| P | 0 to 1.5 | |
| Ni | 0 to 1.0 | |
| Fe | 0 to 0.4 | |
| Sb | 0 to 0.25 | |
| S | 0 to 0.080 | |
| Si | 0 to 0.0050 | |
| Al | 0 to 0.0050 | |
| res. | 0 to 0.7 |
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
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015