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UNS R30605 (L605, Alloy 25, 2.4964) Alloy

R30605 cobalt is a cobalt alloy. It can have a moderately high tensile strength among cobalt alloys. In addition, it has a fairly low heat capacity and a moderately low thermal conductivity.

The properties of R30605 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 R30605 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 30 x 106 psi

Elongation at Break

34 %

Fatigue Strength

260 to 590 MPa 38 to 85 x 103 psi

Poisson's Ratio


Shear Modulus

81 GPa 12 x 106 psi

Tensile Strength: Ultimate (UTS)

1130 to 1900 MPa 160 to 280 x 103 psi

Tensile Strength: Yield (Proof)

470 to 1600 MPa 68 to 230 x 103 psi

Thermal Properties

Latent Heat of Fusion

290 J/g

Melting Completion (Liquidus)

1410 °C 2570 °F

Melting Onset (Solidus)

1330 °C 2430 °F

Specific Heat Capacity

410 J/kg-K 0.1 BTU/lb-°F

Thermal Conductivity

9.6 W/m-K 5.6 BTU/h-ft-°F

Thermal Expansion

12 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

2.0 % IACS

Electrical Conductivity: Equal Weight (Specific)

1.8 % IACS

Otherwise Unclassified Properties


9.6 g/cm3 600 lb/ft3

Embodied Carbon

9.8 kg CO2/kg material

Embodied Energy

140 MJ/kg 60 x 103 BTU/lb

Embodied Water

450 L/kg 53 gal/lb

Common Calculations

Stiffness to Weight: Axial

12 points

Stiffness to Weight: Bending

21 points

Strength to Weight: Axial

33 to 55 points

Strength to Weight: Bending

25 to 36 points

Thermal Diffusivity

2.5 mm2/s

Thermal Shock Resistance

31 to 52 points

Alloy Composition

Cobalt (Co)Co 46.4 to 57
Chromium (Cr)Cr 19 to 21
Tungsten (W)W 14 to 16
Nickel (Ni)Ni 9.0 to 11
Manganese (Mn)Mn 1.0 to 2.0
Iron (Fe)Fe 0 to 3.0
Silicon (Si)Si 0 to 0.4
Carbon (C)C 0.050 to 0.15
Phosphorus (P)P 0 to 0.040
Sulfur (S)S 0 to 0.030

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

Followup Questions

Similar Alloys

Further Reading

ASTM F90: Standard Specification for Wrought Cobalt-20Chromium-15Tungsten-10Nickel Alloy for Surgical Implant Applications (UNS R30605)

ASTM F1091: Standard Specification for Wrought Cobalt-20Chromium-15Tungsten-10Nickel Alloy Surgical Fixation Wire (UNS R30605)

ISO 5832-5: Implants for Surgery - Metallic Materials - Part 5: Wrought Cobalt-Chromium-Tungsten-Nickel Alloy

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