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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.

Copper (Cu) 73 to 77
Zinc (Zn) 18.4 to 24.3
Silicon (Si) 2.7 to 3.4
Tin (Sn) 0 to 0.2
Phosphorus (P) 0.040 to 0.15
Manganese (Mn) 0 to 0.1
Nickel (Ni) 0 to 0.1
Iron (Fe) 0 to 0.1
Lead (Pb) 0 to 0.090
Residuals 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