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UNS C31400 Leaded Hardware Bronze

C31400 bronze is a bronze formulated for primary forming into wrought products. It can have a moderately low tensile strength among wrought bronzes. In addition, it has a moderately low embodied energy and a moderately high electrical conductivity.

The properties of C31400 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 C31400 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

6.8 to 29 %

Poisson's Ratio


Shear Modulus

42 GPa 6.1 x 106 psi

Shear Strength

180 to 240 MPa 26 to 35 x 103 psi

Tensile Strength: Ultimate (UTS)

270 to 420 MPa 40 to 60 x 103 psi

Tensile Strength: Yield (Proof)

78 to 310 MPa 11 to 45 x 103 psi

Thermal Properties

Latent Heat of Fusion

200 J/g

Maximum Temperature: Mechanical

180 °C 350 °F

Melting Completion (Liquidus)

1040 °C 1900 °F

Melting Onset (Solidus)

1010 °C 1850 °F

Specific Heat Capacity

380 J/kg-K 0.091 BTU/lb-°F

Thermal Conductivity

180 W/m-K 100 BTU/h-ft-°F

Thermal Expansion

18 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

42 % IACS

Electrical Conductivity: Equal Weight (Specific)

43 % IACS

Otherwise Unclassified Properties

Base Metal Price

29 % relative


8.8 g/cm3 550 lb/ft3

Embodied Carbon

2.6 kg CO2/kg material

Embodied Energy

42 MJ/kg 18 x 103 BTU/lb

Embodied Water

310 L/kg 37 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

26 to 59 MJ/m3

Resilience: Unit (Modulus of Resilience)

28 to 420 kJ/m3

Stiffness to Weight: Axial

7.1 points

Stiffness to Weight: Bending

18 points

Strength to Weight: Axial

8.7 to 13 points

Strength to Weight: Bending

11 to 14 points

Thermal Diffusivity

54 mm2/s

Thermal Shock Resistance

9.6 to 15 points

Alloy Composition

Among wrought copper alloys, the composition of C31400 bronze is notable for containing a comparatively high amount of lead (Pb) and including nickel (Ni). Lead is used to improve machinability and bearing properties, at the cost of toxicity. Nickel is used to improve strength (particularly at elevated temperatures) and corrosion resistance.

Copper (Cu)Cu 87.5 to 90.5
Zinc (Zn)Zn 5.8 to 11.2
Lead (Pb)Pb 1.3 to 2.5
Nickel (Ni)Ni 0 to 0.7
Iron (Fe)Fe 0 to 0.1
Residualsres. 0 to 0.4

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

Followup Questions

Similar Alloys

Further Reading

ASTM B140: Standard Specification for Copper-Zinc-Lead (Red Brass or Hardware Bronze) Rod, Bar, and Shapes

ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001