UNS C51900 (CW452K) Phosphor Bronze
C51900 bronze is a bronze formulated for primary forming into wrought products. CW452K is the EN numeric designation for this material. C51900 is the UNS number. Additionally, the EN chemical designation is CuSn6. And the British Standard (BS) designation is PB103.
It has a moderately high base cost and a moderately low melting temperature among wrought bronzes.
The properties of C51900 bronze include three 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 C51900 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
14 to 29 %
Poisson's Ratio
0.34
Rockwell B Hardness
42 to 91
Rockwell Superficial 30T Hardness
45 to 76
Shear Modulus
42 GPa 6.0 x 106 psi
Shear Strength
320 to 370 MPa 47 to 54 x 103 psi
Tensile Strength: Ultimate (UTS)
380 to 620 MPa 55 to 89 x 103 psi
Tensile Strength: Yield (Proof)
390 to 570 MPa 57 to 82 x 103 psi
Thermal Properties
Latent Heat of Fusion
200 J/g
Maximum Temperature: Mechanical
180 °C 360 °F
Melting Completion (Liquidus)
1040 °C 1900 °F
Melting Onset (Solidus)
930 °C 1700 °F
Specific Heat Capacity
380 J/kg-K 0.090 BTU/lb-°F
Thermal Conductivity
66 W/m-K 38 BTU/h-ft-°F
Thermal Expansion
18 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
14 % IACS
Electrical Conductivity: Equal Weight (Specific)
14 % IACS
Otherwise Unclassified Properties
Base Metal Price
33 % relative
Density
8.8 g/cm3 550 lb/ft3
Embodied Carbon
3.2 kg CO2/kg material
Embodied Energy
51 MJ/kg 22 x 103 BTU/lb
Embodied Water
360 L/kg 42 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
55 to 180 MJ/m3
Resilience: Unit (Modulus of Resilience)
680 to 1450 kJ/m3
Stiffness to Weight: Axial
7.0 points
Stiffness to Weight: Bending
18 points
Strength to Weight: Axial
12 to 19 points
Strength to Weight: Bending
13 to 18 points
Thermal Diffusivity
20 mm2/s
Thermal Shock Resistance
14 to 22 points
Alloy Composition
Among wrought copper alloys, the composition of C51900 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 | 91.7 to 95 | |
| Sn | 5.0 to 7.0 | |
| 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 B103: Standard Specification for Phosphor Bronze Plate, Sheet, Strip, and Rolled Bar
ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001