# UNS C68400 Silicon-Manganese Brass

C68400 brass is a brass formulated for primary forming into wrought products. Cited properties are appropriate for the M30 (as hot extruded) condition.

It has the highest electrical conductivity among wrought brasses. In addition, it has a moderately low melting temperature and a moderately low thermal conductivity.

The graph bars on the material properties cards below compare C68400 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

Brinell Hardness

150

Elastic (Young's, Tensile) Modulus

110 *GPa* 15 *x 10 ^{6} psi*

Elongation at Break

18 *%*

Poisson's Ratio

0.31

Shear Modulus

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

Shear Strength

330 *MPa* 48 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

540 *MPa* 78 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

310 *MPa* 45 *x 10 ^{3} psi*

## Thermal Properties

Latent Heat of Fusion

210 *J/g*

Maximum Temperature: Mechanical

130 *°C* 270 *°F*

Melting Completion (Liquidus)

840 *°C* 1540 *°F*

Melting Onset (Solidus)

820 *°C* 1520 *°F*

Specific Heat Capacity

400 *J/kg-K* 0.1 *BTU/lb-°F*

Thermal Conductivity

66 *W/m-K* 38 *BTU/h-ft-°F*

Thermal Expansion

20 *µm/m-K*

## Electrical Properties

Electrical Conductivity: Equal Volume

87 *% IACS*

Electrical Conductivity: Equal Weight (Specific)

99 *% IACS*

## Otherwise Unclassified Properties

Base Metal Price

23 *% relative*

Density

7.9 *g/cm ^{3}* 490

*lb/ft*

^{3}Embodied Carbon

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

Embodied Energy

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

Embodied Water

320 *L/kg* 38 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

81 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

460 *kJ/m ^{3}*

Stiffness to Weight: Axial

7.5 *points*

Stiffness to Weight: Bending

20 *points*

Strength to Weight: Axial

19 *points*

Strength to Weight: Bending

19 *points*

Thermal Diffusivity

21 *mm ^{2}/s*

Thermal Shock Resistance

18 *points*

## Alloy Composition

Among wrought copper alloys, the composition of C68400 brass is notable for including aluminum (Al) and silicon (Si). Aluminum is used to add strength and oxidation resistance. Silicon is used to increase strength at the expense of ductility. It also lowers the melting temperature and raises the fluidity of the alloy.

Cu | 59 to 64 | |

Zn | 28.6 to 39.3 | |

Si | 1.5 to 2.5 | |

Mn | 0.2 to 1.5 | |

Fe | 0 to 1.0 | |

Ni | 0 to 0.5 | |

Al | 0 to 0.5 | |

Sn | 0 to 0.5 | |

P | 0.030 to 0.3 | |

Pb | 0 to 0.090 | |

B | 0.0010 to 0.030 | |

res. | 0 to 0.5 |

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