# 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 10 ^{6} psi*

Poisson's Ratio

0.32

Shear Modulus

41 *GPa* 5.9 *x 10 ^{6} psi*

Tensile Strength: Ultimate (UTS)

390 *MPa* 57 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

140 *MPa* 20 *x 10 ^{3} 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/cm ^{3}* 520

*lb/ft*

^{3}Embodied Carbon

2.8 *kg CO _{2}/kg material*

Embodied Energy

46 *MJ/kg* 20 *x 10 ^{3} BTU/lb*

Embodied Water

340 *L/kg* 40 *gal/lb*

## Common Calculations

Resilience: Unit (Modulus of Resilience)

90 *kJ/m ^{3}*

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 *mm ^{2}/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