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UNS C67500 (CW721R) Manganese Bronze

C67500 bronze is a bronze formulated for primary forming into wrought products. CW721R is the EN numeric designation for this material. C67500 is the UNS number. Additionally, the EN chemical designation is CuZn40Mn1Pb1AlFeSn. And the British Standard (BS) designation is CZ114. Older literature may refer to this material as ASTM Manganese Bronze Type A, but this is now discouraged.

It has a moderately low base cost and a moderately low melting temperature among wrought bronzes.

The properties of C67500 bronze include five 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 C67500 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

100 GPa 15 x 106 psi

Elongation at Break

14 to 33 %

Poisson's Ratio


Shear Modulus

40 GPa 5.8 x 106 psi

Shear Strength

270 to 350 MPa 40 to 51 x 103 psi

Tensile Strength: Ultimate (UTS)

430 to 580 MPa 63 to 84 x 103 psi

Tensile Strength: Yield (Proof)

170 to 370 MPa 24 to 54 x 103 psi

Thermal Properties

Latent Heat of Fusion

170 J/g

Maximum Temperature: Mechanical

120 °C 250 °F

Melting Completion (Liquidus)

890 °C 1630 °F

Melting Onset (Solidus)

870 °C 1590 °F

Specific Heat Capacity

390 J/kg-K 0.092 BTU/lb-°F

Thermal Conductivity

110 W/m-K 61 BTU/h-ft-°F

Thermal Expansion

21 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

24 % IACS

Electrical Conductivity: Equal Weight (Specific)

27 % IACS

Otherwise Unclassified Properties

Base Metal Price

23 % relative


8.0 g/cm3 500 lb/ft3

Embodied Carbon

2.8 kg CO2/kg material

Embodied Energy

47 MJ/kg 20 x 103 BTU/lb

Embodied Water

330 L/kg 39 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

61 to 130 MJ/m3

Resilience: Unit (Modulus of Resilience)

130 to 650 kJ/m3

Stiffness to Weight: Axial

7.3 points

Stiffness to Weight: Bending

20 points

Strength to Weight: Axial

15 to 20 points

Strength to Weight: Bending

16 to 19 points

Thermal Diffusivity

34 mm2/s

Thermal Shock Resistance

14 to 19 points

Alloy Composition

Among wrought copper alloys, the composition of C67500 bronze is notable for including aluminum (Al) and containing a comparatively high amount of iron (Fe). Aluminum is used to add strength and oxidation resistance. Iron is used to increase strength inexpensively.

Copper (Cu)Cu 57 to 60
Zinc (Zn)Zn 35.1 to 41.7
Iron (Fe)Fe 0.8 to 2.0
Tin (Sn)Sn 0.5 to 1.5
Manganese (Mn)Mn 0.050 to 0.5
Aluminum (Al)Al 0 to 0.25
Lead (Pb)Pb 0 to 0.2
Residualsres. 0 to 0.5

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

Followup Questions

Similar Alloys

Further Reading

ASTM B138: Standard Specification for Manganese Bronze Rod, Bar, and Shapes

ASTM B124: Standard Specification for Copper and Copper Alloy Forging Rod, Bar, and Shapes

ASTM B283: Standard Specification for Copper and Copper-Alloy Die Forgings (Hot-Pressed)

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