UNS C51000 (CW451K) Phosphor Bronze
C51000 bronze is a bronze formulated for primary forming into wrought products. CW451K is the EN numeric designation for this material. C51000 is the UNS number. Additionally, the EN chemical designation is CuSn5. And the British Standard (BS) designation is PB102. Older literature may refer to this material as ASTM Phosphor Bronze Grade A1, but this is now discouraged.
It has a moderately high base cost among the wrought bronzes in the database.
The properties of C51000 bronze include eight 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 C51000 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
2.7 to 64 %
Poisson's Ratio
0.34
Rockwell B Hardness
26 to 97
Rockwell Superficial 30T Hardness
42 to 80
Shear Modulus
42 GPa 6.1 x 106 psi
Shear Strength
250 to 460 MPa 36 to 66 x 103 psi
Tensile Strength: Ultimate (UTS)
330 to 780 MPa 47 to 110 x 103 psi
Tensile Strength: Yield (Proof)
130 to 750 MPa 19 to 110 x 103 psi
Thermal Properties
Latent Heat of Fusion
200 J/g
Maximum Temperature: Mechanical
190 °C 370 °F
Melting Completion (Liquidus)
1050 °C 1930 °F
Melting Onset (Solidus)
960 °C 1770 °F
Specific Heat Capacity
380 J/kg-K 0.090 BTU/lb-°F
Thermal Conductivity
77 W/m-K 44 BTU/h-ft-°F
Thermal Expansion
18 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
18 % IACS
Electrical Conductivity: Equal Weight (Specific)
18 % IACS
Otherwise Unclassified Properties
Base Metal Price
33 % relative
Density
8.8 g/cm3 550 lb/ft3
Embodied Carbon
3.1 kg CO2/kg material
Embodied Energy
50 MJ/kg 21 x 103 BTU/lb
Embodied Water
350 L/kg 42 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
7.0 to 490 MJ/m3
Resilience: Unit (Modulus of Resilience)
75 to 2490 kJ/m3
Stiffness to Weight: Axial
7.0 points
Stiffness to Weight: Bending
18 points
Strength to Weight: Axial
10 to 25 points
Strength to Weight: Bending
12 to 21 points
Thermal Diffusivity
23 mm2/s
Thermal Shock Resistance
12 to 28 points
Alloy Composition
Among wrought copper alloys, the composition of C51000 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.
| Cu | 92.9 to 95.5 | |
| Sn | 4.5 to 5.8 | |
| P | 0.030 to 0.35 | |
| Zn | 0 to 0.3 | |
| Fe | 0 to 0.1 | |
| Pb | 0 to 0.050 | |
| 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
Copper: Its Trade, Manufacture, Use, and Environmental Status, Gunter Joseph, 2001