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UNS C67000 (CW704R) Manganese Bronze

C67000 bronze is a bronze formulated for primary forming into wrought products. CW704R is the EN numeric designation for this material. C67000 is the UNS number. Additionally, the EN chemical designation is CuZn23Al6Mn4Fe3Pb.

It has a moderately low base cost among wrought bronzes. In addition, it has a fairly low melting temperature and can have a moderately high tensile strength.

The properties of C67000 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 C67000 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

5.6 to 11 %

Poisson's Ratio


Shear Modulus

42 GPa 6.1 x 106 psi

Shear Strength

390 to 510 MPa 57 to 75 x 103 psi

Tensile Strength: Ultimate (UTS)

660 to 880 MPa 95 to 130 x 103 psi

Tensile Strength: Yield (Proof)

350 to 540 MPa 51 to 78 x 103 psi

Thermal Properties

Latent Heat of Fusion

190 J/g

Maximum Temperature: Mechanical

160 °C 310 °F

Melting Completion (Liquidus)

900 °C 1650 °F

Melting Onset (Solidus)

850 °C 1570 °F

Specific Heat Capacity

410 J/kg-K 0.1 BTU/lb-°F

Thermal Conductivity

99 W/m-K 57 BTU/h-ft-°F

Thermal Expansion

20 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

22 % IACS

Electrical Conductivity: Equal Weight (Specific)

25 % IACS

Otherwise Unclassified Properties

Base Metal Price

23 % relative


7.9 g/cm3 500 lb/ft3

Embodied Carbon

2.9 kg CO2/kg material

Embodied Energy

49 MJ/kg 21 x 103 BTU/lb

Embodied Water

350 L/kg 42 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

43 to 62 MJ/m3

Resilience: Unit (Modulus of Resilience)

560 to 1290 kJ/m3

Stiffness to Weight: Axial

7.8 points

Stiffness to Weight: Bending

20 points

Strength to Weight: Axial

23 to 31 points

Strength to Weight: Bending

21 to 26 points

Thermal Diffusivity

30 mm2/s

Thermal Shock Resistance

21 to 29 points

Alloy Composition

Among wrought copper alloys, the composition of C67000 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 63 to 68
Zinc (Zn)Zn 21.8 to 32.5
Aluminum (Al)Al 3.0 to 6.0
Manganese (Mn)Mn 2.5 to 5.0
Iron (Fe)Fe 2.0 to 4.0
Tin (Sn)Sn 0 to 0.5
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

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

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015