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SAE-AISI M6 (T11306) Cobalt High-Speed Steel

SAE-AISI M6 steel is a tool steel. M6 is the designation in both the SAE and AISI systems for this material. T11306 is the UNS number.

The properties of SAE-AISI M6 steel 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 SAE-AISI M6 steel to: tool steels (top), all iron alloys (middle), 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

200 GPa 29 x 106 psi

Poisson's Ratio


Shear Modulus

77 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

840 to 2210 MPa 120 to 320 x 103 psi

Thermal Properties

Latent Heat of Fusion

260 J/g

Melting Completion (Liquidus)

1560 °C 2840 °F

Melting Onset (Solidus)

1510 °C 2750 °F

Specific Heat Capacity

440 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

17 W/m-K 10 BTU/h-ft-°F

Thermal Expansion

12 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

39 % relative


8.4 g/cm3 520 lb/ft3

Embodied Carbon

8.0 kg CO2/kg material

Embodied Energy

120 MJ/kg 50 x 103 BTU/lb

Embodied Water

160 L/kg 19 gal/lb

Common Calculations

PREN (Pitting Resistance)


Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

23 points

Strength to Weight: Axial

28 to 73 points

Strength to Weight: Bending

24 to 45 points

Thermal Diffusivity

4.7 mm2/s

Thermal Shock Resistance

26 to 68 points

Alloy Composition

Iron (Fe)Fe 68.8 to 74.6
Cobalt (Co)Co 11 to 13
Molybdenum (Mo)Mo 4.5 to 5.5
Tungsten (W)W 3.8 to 4.8
Chromium (Cr)Cr 3.8 to 4.5
Vanadium (V)V 1.3 to 1.7
Carbon (C)C 0.75 to 0.85
Silicon (Si)Si 0.2 to 0.45
Manganese (Mn)Mn 0.15 to 0.4
Phosphorus (P)P 0 to 0.030
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 A600: Standard Specification for Tool Steel High Speed

Tool Steels, 5th ed., George Roberts et al., 1998

Tool Steels: Properties and Performance, Rafael A. Mesquita (editor), 2016

ASM Specialty Handbook: Carbon and Alloy Steels, J. R. Davis (editor), 1996