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UNS R30008 (ASTM F1058 Grade 2) Cobalt

R30008 cobalt is a cobalt alloy. ASTM F1058 Grade 2 is the ASTM designation for this material. R30008 is the UNS number. It has a moderately high melting temperature among the cobalt alloys in the database.

The properties of R30008 cobalt include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare R30008 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

210 GPa 31 x 106 psi

Elongation at Break

1.1 to 73 %

Fatigue Strength

320 to 530 MPa 46 to 77 x 103 psi

Poisson's Ratio


Shear Modulus

83 GPa 12 x 106 psi

Tensile Strength: Ultimate (UTS)

950 to 1700 MPa 140 to 250 x 103 psi

Tensile Strength: Yield (Proof)

500 to 1080 MPa 73 to 160 x 103 psi

Thermal Properties

Latent Heat of Fusion

320 J/g

Melting Completion (Liquidus)

1400 °C 2550 °F

Melting Onset (Solidus)

1330 °C 2430 °F

Specific Heat Capacity

450 J/kg-K 0.11 BTU/lb-°F

Thermal Expansion

13 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

95 % relative


8.4 g/cm3 530 lb/ft3

Embodied Carbon

8.1 kg CO2/kg material

Embodied Energy

110 MJ/kg 46 x 103 BTU/lb

Embodied Water

400 L/kg 48 gal/lb

Common Calculations

Resilience: Unit (Modulus of Resilience)

590 to 2720 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

31 to 56 points

Strength to Weight: Bending

25 to 37 points

Thermal Shock Resistance

25 to 44 points

Alloy Composition

Cobalt (Co)Co 39 to 42
Chromium (Cr)Cr 18.5 to 21.5
Nickel (Ni)Ni 15 to 18
Iron (Fe)Fe 7.6 to 20
Molybdenum (Mo)Mo 6.5 to 7.5
Manganese (Mn)Mn 1.0 to 2.0
Silicon (Si)Si 0 to 1.2
Carbon (C)C 0 to 0.15
Phosphorus (P)P 0 to 0.015
Sulfur (S)S 0 to 0.015
Boron (B)B 0 to 0.0010

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

Followup Questions

Similar Alloys

Further Reading

ASTM F1058: Standard Specification for Wrought 40Cobalt-20Chromium-16Iron-15Nickel-7Molybdenum Alloy Wire and Strip for Surgical Implant Applications (UNS R30003 and UNS R30008)

ISO 5832-7: Implants for Surgery - Metallic Materials - Part 7: Forgeable and Cold-Formed Cobalt-Chromium-Nickel-Molybdenum-Iron Alloy