# UNS R31233 Cobalt

R31233 cobalt is a cobalt alloy. It is typically furnished in the annealed (O) condition. It has a moderately high melting temperature and a moderately high ductility relative to other cobalt alloys. The graph bars on the material properties cards below compare R31233 cobalt to other cobalt alloys (top) and the entire database (bottom). The length of each bar shows the given value as a % of the largest value in the relevant set.

## 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