# UNS R30021 Co-Cr-W Alloy

R30021 cobalt is a cobalt alloy. Cited properties are appropriate for the annealed condition. It has a moderately high thermal conductivity among cobalt alloys. In addition, it has a very low melting temperature and a fairly low tensile strength.

The graph bars on the material properties cards below compare R30021 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

Compressive (Crushing) Strength

1300 *MPa* 190 *x 10 ^{3} psi*

Elastic (Young's, Tensile) Modulus

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

Elongation at Break

9.0 *%*

Fatigue Strength

250 *MPa* 37 *x 10 ^{3} psi*

Poisson's Ratio

0.29

Rockwell C Hardness

32

Shear Modulus

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

Tensile Strength: Ultimate (UTS)

700 *MPa* 100 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

500 *MPa* 73 *x 10 ^{3} psi*

## Thermal Properties

Latent Heat of Fusion

330 *J/g*

Melting Completion (Liquidus)

1350 *°C* 2470 *°F*

Melting Onset (Solidus)

1190 *°C* 2170 *°F*

Specific Heat Capacity

450 *J/kg-K* 0.11 *BTU/lb-°F*

Thermal Conductivity

15 *W/m-K* 8.4 *BTU/h-ft-°F*

Thermal Expansion

11 *µm/m-K*

## Electrical Properties

Electrical Conductivity: Equal Volume

1.9 *% IACS*

Electrical Conductivity: Equal Weight (Specific)

2.1 *% IACS*

## Otherwise Unclassified Properties

Density

8.4 *g/cm ^{3}* 530

*lb/ft*

^{3}Embodied Carbon

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

Embodied Energy

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

Embodied Water

520 *L/kg* 62 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

57 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

570 *kJ/m ^{3}*

Stiffness to Weight: Axial

15 *points*

Stiffness to Weight: Bending

24 *points*

Strength to Weight: Axial

23 *points*

Strength to Weight: Bending

21 *points*

Thermal Diffusivity

3.8 *mm ^{2}/s*

Thermal Shock Resistance

21 *points*

## Alloy Composition

Co | 61.7 to 67.3 | |

Cr | 26 to 29 | |

Mo | 4.5 to 6.0 | |

Ni | 2.0 to 3.0 | |

Fe | 0 to 3.0 | |

Si | 0 to 1.5 | |

C | 0.2 to 0.35 |

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

## Followup Questions

## Similar Alloys

## Further Reading

Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993

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