UNS C54400 (CW456K) Phosphor Bronze
C54400 bronze is a bronze formulated for primary forming into wrought products. CW456K is the EN numeric designation for this material. C54400 is the UNS number. Additionally, the EN chemical designation is CuSn4Pb4Zn4. Older literature may refer to this material as ASTM Bronze Type B2, but this is now discouraged.
It has a moderately low heat capacity and a moderately low melting temperature among wrought bronzes.
The properties of C54400 bronze include seven 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 C54400 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 16 x 106 psi
Poisson's Ratio
0.34
Rockwell B Hardness
67 to 93
Rockwell Superficial 30T Hardness
33 to 79
Shear Modulus
40 GPa 5.8 x 106 psi
Tensile Strength: Ultimate (UTS)
330 to 720 MPa 47 to 100 x 103 psi
Thermal Properties
Latent Heat of Fusion
190 J/g
Maximum Temperature: Mechanical
170 °C 340 °F
Melting Completion (Liquidus)
1000 °C 1830 °F
Melting Onset (Solidus)
930 °C 1700 °F
Specific Heat Capacity
370 J/kg-K 0.088 BTU/lb-°F
Thermal Conductivity
86 W/m-K 50 BTU/h-ft-°F
Thermal Expansion
18 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
19 % IACS
Electrical Conductivity: Equal Weight (Specific)
19 % IACS
Otherwise Unclassified Properties
Base Metal Price
31 % relative
Density
8.9 g/cm3 550 lb/ft3
Embodied Carbon
2.9 kg CO2/kg material
Embodied Energy
48 MJ/kg 20 x 103 BTU/lb
Embodied Water
340 L/kg 41 gal/lb
Common Calculations
Stiffness to Weight: Axial
6.8 points
Stiffness to Weight: Bending
18 points
Strength to Weight: Axial
10 to 22 points
Strength to Weight: Bending
12 to 20 points
Thermal Diffusivity
26 mm2/s
Thermal Shock Resistance
12 to 26 points
Alloy Composition
Among wrought copper alloys, the composition of C54400 bronze is notable for containing a comparatively high amount of lead (Pb) and including phosphorus (P). Lead is used to improve machinability and bearing properties, at the cost of toxicity. Phosphorus is used as an alloy deoxidizer, and to reduce vulnerability to dezincification.
| Cu | 85.4 to 91.5 | |
| Sn | 3.5 to 4.5 | |
| Pb | 3.5 to 4.5 | |
| Zn | 1.5 to 4.5 | |
| P | 0.010 to 0.5 | |
| Fe | 0 to 0.1 | |
| res. | 0 to 0.5 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B139: Standard Specification for Phosphor Bronze Rod, Bar, and Shapes
ASTM B103: Standard Specification for Phosphor Bronze Plate, Sheet, Strip, and Rolled Bar
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