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UNS C86400 Leaded Manganese Bronze

C86400 bronze is a bronze formulated for casting. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. C86400 is the UNS number for this material. Older literature may refer to this material as ASTM Alloy 7A, but this is now discouraged.

It has a very low base cost among cast bronzes. In addition, it has a very high electrical conductivity and a fairly high thermal conductivity.

The graph bars on the material properties cards below compare C86400 bronze to: cast 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

100 GPa 15 x 106 psi

Elongation at Break

17 %

Poisson's Ratio

0.31

Shear Modulus

40 GPa 5.8 x 106 psi

Tensile Strength: Ultimate (UTS)

470 MPa 68 x 103 psi

Tensile Strength: Yield (Proof)

150 MPa 22 x 103 psi

Thermal Properties

Latent Heat of Fusion

170 J/g

Maximum Temperature: Mechanical

120 °C 250 °F

Melting Completion (Liquidus)

880 °C 1620 °F

Melting Onset (Solidus)

860 °C 1580 °F

Specific Heat Capacity

390 J/kg-K 0.093 BTU/lb-°F

Thermal Conductivity

88 W/m-K 51 BTU/h-ft-°F

Thermal Expansion

21 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

19 % IACS

Electrical Conductivity: Equal Weight (Specific)

22 % IACS

Otherwise Unclassified Properties

Base Metal Price

23 % relative

Density

7.9 g/cm3 500 lb/ft3

Embodied Carbon

2.8 kg CO2/kg material

Embodied Energy

48 MJ/kg 21 x 103 BTU/lb

Embodied Water

330 L/kg 40 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

63 MJ/m3

Resilience: Unit (Modulus of Resilience)

110 kJ/m3

Stiffness to Weight: Axial

7.3 points

Stiffness to Weight: Bending

20 points

Strength to Weight: Axial

16 points

Strength to Weight: Bending

17 points

Thermal Diffusivity

29 mm2/s

Thermal Shock Resistance

16 points

Alloy Composition

Among cast copper alloys, the composition of C86400 bronze is notable for containing a comparatively high amount of iron (Fe) and including manganese (Mn). Iron is used to increase strength inexpensively. Manganese is used to improve strength without a proportional reduction in ductility.

Copper (Cu) 56 to 62
Zinc (Zn) 34 to 42
Iron (Fe) 0.4 to 2.0
Aluminum (Al) 0.5 to 1.5
Tin (Sn) 0.5 to 1.5
Lead (Pb) 0.5 to 1.5
Manganese (Mn) 0.1 to 1.0
Nickel (Ni) 0 to 1.0
Residuals 0 to 1.0

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

Followup Questions

Similar Alloys

Further Reading

ASTM B271: Standard Specification for Copper-Base Alloy Centrifugal Castings

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