SAE-AISI M42 (T11342) Molybdenum High-Speed Steel

SAE-AISI M42 steel is a tool steel. M42 is the designation in both the SAE and AISI systems for this material. T11342 is the UNS number.

The properties of SAE-AISI M42 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 M42 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.

Annealed M42 Tool Steel Hardened M42 Tool Steel

Mechanical Properties

Elastic (Young's, Tensile) Modulus

200 GPa 29 x 10⁶ psi

Poisson's Ratio

0.29

Shear Modulus

78 GPa 11 x 10⁶ psi

Tensile Strength: Ultimate (UTS)

810 to 2310 MPa 120 to 340 x 10³ psi

Thermal Properties

Latent Heat of Fusion

270 J/g

Melting Completion (Liquidus)

1540 °C 2800 °F

Melting Onset (Solidus)

1490 °C 2710 °F

Specific Heat Capacity

450 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

20 W/m-K 11 BTU/h-ft-°F

Thermal Expansion

12 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

30 % relative

Density

8.2 g/cm³ 510 lb/ft³

Embodied Carbon

7.4 kg CO₂/kg material

Embodied Energy

100 MJ/kg 44 x 10³ BTU/lb

Embodied Water

140 L/kg 17 gal/lb

Common Calculations

PREN (Pitting Resistance)

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

28 to 79 points

Strength to Weight: Bending

24 to 48 points

Thermal Diffusivity

5.4 mm²/s

Thermal Shock Resistance

25 to 71 points

Alloy Composition

Iron (Fe)Fe		76.3 to 81
Molybdenum (Mo)Mo		9.0 to 10
Cobalt (Co)Co		7.8 to 8.8
Chromium (Cr)Cr		3.5 to 4.3
Tungsten (W)W		1.2 to 1.9
Vanadium (V)V		1.0 to 1.4
Carbon (C)C		1.1 to 1.2
Silicon (Si)Si		0.15 to 0.65
Manganese (Mn)Mn		0.15 to 0.4
Nickel (Ni)Ni		0 to 0.3
Copper (Cu)Cu		0 to 0.25
Phosphorus (P)P		0 to 0.030
Sulfur (S)S		0 to 0.030