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UNS C51100 (CW450K) Phosphor Bronze

C51100 bronze is a bronze formulated for primary forming into wrought products. CW450K is the EN numeric designation for this material. C51100 is the UNS number. Additionally, the EN chemical designation is CuSn4. And the British Standard (BS) designation is PB101. Older literature may refer to this material as ASTM Phosphor Bronze Grade A, but this is now discouraged.

It has a moderately high base cost among the wrought bronzes in the database.

The properties of C51100 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 C51100 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

Elongation at Break

2.5 to 50 %

Poisson's Ratio

0.34

Rockwell B Hardness

67 to 93

Rockwell Superficial 30T Hardness

33 to 79

Shear Modulus

42 GPa 6.1 x 106 psi

Shear Strength

230 to 410 MPa 33 to 59 x 103 psi

Tensile Strength: Ultimate (UTS)

330 to 720 MPa 47 to 100 x 103 psi

Tensile Strength: Yield (Proof)

93 to 700 MPa 13 to 100 x 103 psi

Thermal Properties

Latent Heat of Fusion

200 J/g

Maximum Temperature: Mechanical

190 °C 370 °F

Melting Completion (Liquidus)

1060 °C 1950 °F

Melting Onset (Solidus)

970 °C 1790 °F

Specific Heat Capacity

380 J/kg-K 0.090 BTU/lb-°F

Thermal Conductivity

84 W/m-K 49 BTU/h-ft-°F

Thermal Expansion

18 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

20 % IACS

Electrical Conductivity: Equal Weight (Specific)

20 % IACS

Otherwise Unclassified Properties

Base Metal Price

32 % relative

Density

8.9 g/cm3 550 lb/ft3

Embodied Carbon

3.0 kg CO2/kg material

Embodied Energy

48 MJ/kg 21 x 103 BTU/lb

Embodied Water

340 L/kg 41 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

18 to 140 MJ/m3

Resilience: Unit (Modulus of Resilience)

38 to 2170 kJ/m3

Stiffness to Weight: Axial

7.1 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

25 mm2/s

Thermal Shock Resistance

12 to 26 points

Alloy Composition

Among wrought copper alloys, the composition of C51100 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) 93.8 to 96.5
Tin (Sn) 3.5 to 4.9
Phosphorus (P) 0.030 to 0.35
Zinc (Zn) 0 to 0.3
Iron (Fe) 0 to 0.1
Lead (Pb) 0 to 0.050
Residuals 0 to 0.5

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

Followup Questions

Similar Alloys

Further Reading

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