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Low Carbon Co-28Cr-6Mo Alloy (ASTM F1537 Alloy 1, ISO 5832-12 Alloy 1, R31537)

R31537 cobalt is a cobalt alloy. ASTM F1537 Alloy 1 is the ASTM designation for this material. R31537 is the UNS number.

The properties of R31537 cobalt include three common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare R31537 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 106 psi

Elongation at Break

14 to 23 %

Fatigue Strength

310 to 480 MPa 45 to 70 x 103 psi

Poisson's Ratio

0.29

Reduction in Area

13 to 23 %

Rockwell C Hardness

25 to 35

Shear Modulus

87 GPa 13 x 106 psi

Tensile Strength: Ultimate (UTS)

1000 to 1340 MPa 150 to 190 x 103 psi

Tensile Strength: Yield (Proof)

590 to 940 MPa 85 to 140 x 103 psi

Thermal Properties

Latent Heat of Fusion

320 J/g

Melting Completion (Liquidus)

1360 °C 2480 °F

Melting Onset (Solidus)

1290 °C 2360 °F

Specific Heat Capacity

450 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

13 W/m-K 7.3 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

8.4 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

530 L/kg 63 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

140 to 200 MJ/m3

Resilience: Unit (Modulus of Resilience)

780 to 1990 kJ/m3

Stiffness to Weight: Axial

15 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

33 to 44 points

Strength to Weight: Bending

26 to 32 points

Thermal Diffusivity

3.4 m2/s

Thermal Shock Resistance

24 to 32 points

Alloy Composition

Cobalt (Co) 58.9 to 69
Chromium (Cr) 26 to 30
Molybdenum (Mo) 5.0 to 7.0
Manganese (Mn) 0 to 1.0
Silicon (Si) 0 to 1.0
Nickel (Ni) 0 to 1.0
Iron (Fe) 0 to 0.75
Nitrogen (N) 0 to 0.25
Carbon (C) 0 to 0.14

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

Followup Questions

Similar Alloys

Further Reading

ISO 5832-12: Implants for Surgery - Metallic Materials - Part 12: Wrought Cobalt-Chromium-Molybdenum Alloy

ASTM F799: Standard Specification for Cobalt-28Chromium-6Molybdenum Alloy Forgings for Surgical Implants (UNS R31537, R31538, R31539)

ASTM F1537: Standard Specification for Wrought Cobalt-28Chromium-6Molybdenum Alloys for Surgical Implants (UNS R31537, UNS R31538, and UNS R31539)

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