UNS C68700 (CW702R) Aluminum Brass
C68700 brass is a brass formulated for primary forming into wrought products. Cited properties are appropriate for the O61 (annealed) temper. CW702R is the EN numeric designation for this material. C68700 is the UNS number. Additionally, the British Standard (BS) designation is CZ110. Older literature may refer to this material as ASTM Aluminum Brass Type B, but this is now discouraged.
It has a moderately low tensile strength among the wrought brasses in the database.
The graph bars on the material properties cards below compare C68700 brass to: wrought brasses (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
Poisson's Ratio
0.32
Shear Modulus
41 GPa 5.9 x 106 psi
Tensile Strength: Ultimate (UTS)
390 MPa 57 x 103 psi
Tensile Strength: Yield (Proof)
140 MPa 20 x 103 psi
Thermal Properties
Latent Heat of Fusion
190 J/g
Maximum Temperature: Mechanical
160 °C 320 °F
Melting Completion (Liquidus)
970 °C 1780 °F
Melting Onset (Solidus)
930 °C 1710 °F
Specific Heat Capacity
400 J/kg-K 0.095 BTU/lb-°F
Thermal Conductivity
100 W/m-K 58 BTU/h-ft-°F
Thermal Expansion
19 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
23 % IACS
Electrical Conductivity: Equal Weight (Specific)
25 % IACS
Otherwise Unclassified Properties
Base Metal Price
26 % relative
Density
8.3 g/cm3 520 lb/ft3
Embodied Carbon
2.8 kg CO2/kg material
Embodied Energy
46 MJ/kg 20 x 103 BTU/lb
Embodied Water
340 L/kg 40 gal/lb
Common Calculations
Resilience: Unit (Modulus of Resilience)
90 kJ/m3
Stiffness to Weight: Axial
7.3 points
Stiffness to Weight: Bending
19 points
Strength to Weight: Axial
13 points
Strength to Weight: Bending
14 points
Thermal Diffusivity
30 mm2/s
Thermal Shock Resistance
13 points
Alloy Composition
Among wrought copper alloys, the composition of C68700 brass is notable for including arsenic (As) and aluminum (Al). Arsenic is used to protect the alloy against dezincification. Aluminum is used to add strength and oxidation resistance.
| Cu | 76 to 79 | |
| Zn | 17.8 to 22.2 | |
| Al | 1.8 to 2.5 | |
| As | 0.020 to 0.1 | |
| Pb | 0 to 0.070 | |
| Fe | 0 to 0.060 | |
| res. | 0 to 0.5 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B111: Standard Specification for Copper and Copper-Alloy Seamless Condenser Tubes and Ferrule Stock
ASM Specialty Handbook: Copper and Copper Alloys, J. R. Davis (editor), 2001