UNS C69300 Silicon Brass
C69300 brass is a brass formulated for primary forming into wrought products. C69300 is the UNS number for this material. Additionally, the EN chemical designation is CuZn21Si3P.
It has a moderately low thermal conductivity among wrought brasses. In addition, it has a moderately low electrical conductivity and a moderately low melting temperature.
The properties of C69300 brass include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare C69300 brass to: wrought 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
8.5 to 15 %
Poisson's Ratio
0.32
Rockwell B Hardness
84 to 88
Shear Modulus
41 GPa 6.0 x 106 psi
Shear Strength
330 to 370 MPa 49 to 54 x 103 psi
Tensile Strength: Ultimate (UTS)
550 to 630 MPa 80 to 92 x 103 psi
Tensile Strength: Yield (Proof)
300 to 390 MPa 43 to 57 x 103 psi
Thermal Properties
Latent Heat of Fusion
240 J/g
Maximum Temperature: Mechanical
160 °C 310 °F
Melting Completion (Liquidus)
880 °C 1620 °F
Melting Onset (Solidus)
860 °C 1570 °F
Specific Heat Capacity
400 J/kg-K 0.1 BTU/lb-°F
Thermal Conductivity
38 W/m-K 22 BTU/h-ft-°F
Thermal Expansion
19 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
8.0 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.8 % IACS
Otherwise Unclassified Properties
Base Metal Price
26 % relative
Density
8.2 g/cm3 510 lb/ft3
Embodied Carbon
2.7 kg CO2/kg material
Embodied Energy
45 MJ/kg 19 x 103 BTU/lb
Embodied Water
310 L/kg 37 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
47 to 70 MJ/m3
Resilience: Unit (Modulus of Resilience)
400 to 700 kJ/m3
Stiffness to Weight: Axial
7.4 points
Stiffness to Weight: Bending
19 points
Strength to Weight: Axial
19 to 21 points
Strength to Weight: Bending
18 to 20 points
Thermal Diffusivity
12 mm2/s
Thermal Shock Resistance
19 to 22 points
Alloy Composition
Among wrought copper alloys, the composition of C69300 brass is notable for including silicon (Si) and phosphorus (P). Silicon is used to increase strength at the expense of ductility. It also lowers the melting temperature and raises the fluidity of the alloy. Phosphorus is used as an alloy deoxidizer, and to reduce vulnerability to dezincification.
| Cu | 73 to 77 | |
| Zn | 18.4 to 24.3 | |
| Si | 2.7 to 3.4 | |
| Sn | 0 to 0.2 | |
| P | 0.040 to 0.15 | |
| Mn | 0 to 0.1 | |
| Ni | 0 to 0.1 | |
| Fe | 0 to 0.1 | |
| Pb | 0 to 0.090 | |
| res. | 0 to 0.5 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993