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 106 psi
Elongation at Break
17 %
Poisson's Ratio
0.31
Shear Modulus
37 GPa 5.4 x 106 psi
Shear Strength
230 MPa 33 x 103 psi
Tensile Strength: Ultimate (UTS)
370 MPa 54 x 103 psi
Tensile Strength: Yield (Proof)
130 MPa 18 x 103 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/cm3 500 lb/ft3
Embodied Carbon
2.6 kg CO2/kg material
Embodied Energy
45 MJ/kg 19 x 103 BTU/lb
Embodied Water
320 L/kg 39 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
48 MJ/m3
Resilience: Unit (Modulus of Resilience)
78 kJ/m3
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 mm2/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