# UNS R31233 Cobalt

R31233 cobalt is a cobalt alloy. Cited properties are appropriate for the annealed condition. It has a moderately high melting temperature and a moderately low thermal conductivity among cobalt alloys. The graph bars on the material properties cards below compare R31233 cobalt to other cobalt alloys (top) 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

220 *GPa* 32 *x 10 ^{6} psi*

Elongation at Break

17 *%*

Fatigue Strength

220 *MPa* 32 *x 10 ^{3} psi*

Poisson's Ratio

0.29

Shear Modulus

85 *GPa* 12 *x 10 ^{6} psi*

Tensile Strength: Ultimate (UTS)

1020 *MPa* 150 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

420 *MPa* 62 *x 10 ^{3} psi*

## Thermal Properties

Latent Heat of Fusion

320 *J/g*

Melting Completion (Liquidus)

1350 *°C* 2470 *°F*

Melting Onset (Solidus)

1330 *°C* 2430 *°F*

Specific Heat Capacity

440 *J/kg-K* 0.11 *BTU/lb-°F*

Thermal Conductivity

12 *W/m-K* 7.1 *BTU/h-ft-°F*

Thermal Expansion

13 *µm/m-K*

## Electrical Properties

Electrical Conductivity: Equal Volume

2.0 *% IACS*

Electrical Conductivity: Equal Weight (Specific)

2.1 *% IACS*

## Otherwise Unclassified Properties

Density

8.6 *g/cm ^{3}* 540

*lb/ft*

^{3}Embodied Carbon

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

Embodied Energy

110 *MJ/kg* 49 *x 10 ^{3} BTU/lb*

Embodied Water

480 *L/kg* 57 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

140 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

410 *kJ/m ^{3}*

Stiffness to Weight: Axial

14 *points*

Stiffness to Weight: Bending

23 *points*

Strength to Weight: Axial

33 *points*

Strength to Weight: Bending

26 *points*

Thermal Diffusivity

3.2 *m ^{2}/s*

Thermal Shock Resistance

25 *points*

## Alloy Composition

Co | 44.7 to 63.3 | |

Cr | 23.5 to 27.5 | |

Ni | 7.0 to 11 | |

Mo | 4.0 to 6.0 | |

Fe | 1.0 to 5.0 | |

W | 1.0 to 3.0 | |

Mn | 0.1 to 1.5 | |

Si | 0.050 to 1.0 | |

N | 0.030 to 0.12 | |

C | 0.020 to 0.1 | |

P | 0 to 0.030 | |

S | 0 to 0.020 | |

B | 0 to 0.015 |

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

## Followup Questions

## Similar Alloys

## Further Reading

ASTM B815: Standard Specification for Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy (UNS R31233) Rod

ASTM B818: Standard Specification for Cobalt-Chromium-Nickel-Molybdenum-Tungsten Alloy (UNS R31233) Plate, Sheet and Strip

ASM Specialty Handbook: Nickel, Cobalt, and Their Alloys, Joseph R. Davis (editor), 2000

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