Menu (ESC)

UNS C65400 Silicon Bronze

C65400 bronze is a bronze formulated for primary forming into wrought products. It has a moderately low electrical conductivity among wrought bronzes. In addition, it can have the highest tensile strength and has a moderately low thermal conductivity.

The properties of C65400 bronze include nine common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare C65400 bronze to: wrought bronzes (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 17 x 106 psi

Elongation at Break

2.6 to 47 %

Poisson's Ratio


Rockwell B Hardness

82 to 120

Rockwell Superficial 30T Hardness

71 to 92

Shear Modulus

43 GPa 6.2 x 106 psi

Shear Strength

350 to 530 MPa 51 to 77 x 103 psi

Tensile Strength: Ultimate (UTS)

500 to 1060 MPa 73 to 150 x 103 psi

Tensile Strength: Yield (Proof)

170 to 910 MPa 25 to 130 x 103 psi

Thermal Properties

Latent Heat of Fusion

260 J/g

Maximum Temperature: Mechanical

200 °C 380 °F

Melting Completion (Liquidus)

1020 °C 1860 °F

Melting Onset (Solidus)

960 °C 1750 °F

Specific Heat Capacity

400 J/kg-K 0.1 BTU/lb-°F

Thermal Conductivity

36 W/m-K 21 BTU/h-ft-°F

Thermal Expansion

17 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.0 % IACS

Electrical Conductivity: Equal Weight (Specific)

7.3 % IACS

Otherwise Unclassified Properties

Base Metal Price

31 % relative


8.7 g/cm3 540 lb/ft3

Embodied Carbon

2.8 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)

10 to 480 MJ/m3

Resilience: Unit (Modulus of Resilience)

130 to 3640 kJ/m3

Stiffness to Weight: Axial

7.3 points

Stiffness to Weight: Bending

19 points

Strength to Weight: Axial

16 to 34 points

Strength to Weight: Bending

16 to 27 points

Thermal Diffusivity

10 mm2/s

Thermal Shock Resistance

18 to 39 points

Alloy Composition

Among wrought copper alloys, the composition of C65400 bronze is notable for including chromium (Cr) and silicon (Si). Chromium additions permits certain types of heat treatment to improve mechanical strength. Silicon is used to increase strength at the expense of ductility. It also lowers the melting temperature and raises the fluidity of the alloy.

Copper (Cu)Cu 93.8 to 96.1
Silicon (Si)Si 2.7 to 3.4
Tin (Sn)Sn 1.2 to 1.9
Zinc (Zn)Zn 0 to 0.5
Chromium (Cr)Cr 0.010 to 0.12
Lead (Pb)Pb 0 to 0.050
Residualsres. 0 to 0.2

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM B96: Standard Specification for Copper-Silicon Alloy Plate, Sheet, Strip, and Rolled Bar for General Purposes and Pressure Vessels

Pressure Vessels: External Pressure Technology, 2nd ed., Carl T. F. Ross, 2011

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