# UNS C38500 (CW608N) Architectural Bronze

C38500 bronze is a bronze formulated for primary forming into wrought products. Cited properties are appropriate for the M20 (as hot rolled) condition. CW608N is the EN numeric designation for this material. C38500 is the UNS number. Additionally, the EN chemical designation is CuZn39Pb3. And the British Standard (BS) designation is CZ123.

It has the lowest base cost among wrought bronzes. In addition, it has a moderately low melting temperature and a moderately high thermal conductivity.

The graph bars on the material properties cards below compare C38500 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

100 *GPa* 15 *x 10 ^{6} psi*

Elongation at Break

17 *%*

Poisson's Ratio

0.31

Shear Modulus

37 *GPa* 5.4 *x 10 ^{6} psi*

Shear Strength

230 *MPa* 33 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

370 *MPa* 54 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

130 *MPa* 18 *x 10 ^{3} psi*

## Thermal Properties

Latent Heat of Fusion

160 *J/g*

Maximum Temperature: Mechanical

110 *°C* 230 *°F*

Melting Completion (Liquidus)

890 *°C* 1630 *°F*

Melting Onset (Solidus)

880 *°C* 1610 *°F*

Specific Heat Capacity

380 *J/kg-K* 0.090 *BTU/lb-°F*

Thermal Conductivity

120 *W/m-K* 71 *BTU/h-ft-°F*

Thermal Expansion

21 *µm/m-K*

## Electrical Properties

Electrical Conductivity: Equal Volume

28 *% IACS*

Electrical Conductivity: Equal Weight (Specific)

31 *% IACS*

## Otherwise Unclassified Properties

Base Metal Price

22 *% relative*

Density

8.1 *g/cm ^{3}* 500

*lb/ft*

^{3}Embodied Carbon

2.6 *kg CO _{2}/kg material*

Embodied Energy

45 *MJ/kg* 19 *x 10 ^{3} BTU/lb*

Embodied Water

320 *L/kg* 39 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

48 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

78 *kJ/m ^{3}*

Stiffness to Weight: Axial

7.0 *points*

Stiffness to Weight: Bending

19 *points*

Strength to Weight: Axial

13 *points*

Strength to Weight: Bending

14 *points*

Thermal Diffusivity

40 *mm ^{2}/s*

Thermal Shock Resistance

12 *points*

## Alloy Composition

Among wrought copper alloys, the composition of C38500 bronze 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.

Cu | 55 to 59 | |

Zn | 36.7 to 42.5 | |

Pb | 2.5 to 3.5 | |

Fe | 0 to 0.35 | |

res. | 0 to 0.5 |

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

## Followup Questions

## Similar Alloys

## Further Reading

ASTM B455: Standard Specification for Copper-Zinc-Lead Alloy (Leaded-Brass) Extruded Shapes

Copper: Its Trade, Manufacture, Use, and Environmental Status, Gunter Joseph, 2001

Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993