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.
| Cu | 56 to 62 | |
| Zn | 34 to 42 | |
| Fe | 0.4 to 2.0 | |
| Al | 0.5 to 1.5 | |
| Sn | 0.5 to 1.5 | |
| Pb | 0.5 to 1.5 | |
| Mn | 0.1 to 1.0 | |
| Ni | 0 to 1.0 | |
| res. | 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