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UNS C53400 (CW458K) Leaded Phosphor Bronze

C53400 bronze is a bronze formulated for primary forming into wrought products. CW458K is the EN numeric designation for this material. C53400 is the UNS number. Additionally, the EN chemical designation is CuSn5Pb1. Older literature may refer to this material as ASTM Bronze Type B1, but this is now discouraged.

It has a moderately high base cost and a moderately low melting temperature among wrought bronzes.

The properties of C53400 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 C53400 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


Rockwell B Hardness

67 to 93

Rockwell Superficial 30T Hardness

33 to 79

Shear Modulus

42 GPa 6.0 x 106 psi

Tensile Strength: Ultimate (UTS)

330 to 720 MPa 47 to 100 x 103 psi

Thermal Properties

Latent Heat of Fusion

200 J/g

Maximum Temperature: Mechanical

180 °C 360 °F

Melting Completion (Liquidus)

1050 °C 1920 °F

Melting Onset (Solidus)

950 °C 1750 °F

Specific Heat Capacity

380 J/kg-K 0.090 BTU/lb-°F

Thermal Conductivity

69 W/m-K 40 BTU/h-ft-°F

Thermal Expansion

18 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

15 % IACS

Electrical Conductivity: Equal Weight (Specific)

15 % IACS

Otherwise Unclassified Properties

Base Metal Price

32 % relative


8.9 g/cm3 550 lb/ft3

Embodied Carbon

3.0 kg CO2/kg material

Embodied Energy

49 MJ/kg 21 x 103 BTU/lb

Embodied Water

350 L/kg 41 gal/lb

Common Calculations

Stiffness to Weight: Axial

7.0 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

21 mm2/s

Thermal Shock Resistance

12 to 26 points

Alloy Composition

Among wrought copper alloys, the composition of C53400 bronze is notable for including phosphorus (P) and tin (Sn). Phosphorus is used as an alloy deoxidizer, and to reduce vulnerability to dezincification. Tin is used to improve strength, bearing properties, and corrosion resistance against certain types of media.

Copper (Cu)Cu 91.8 to 95.7
Tin (Sn)Sn 3.5 to 5.8
Lead (Pb)Pb 0.8 to 1.2
Phosphorus (P)P 0.030 to 0.35
Zinc (Zn)Zn 0 to 0.3
Iron (Fe)Fe 0 to 0.1
Residualsres. 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