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SAE-AISI T4 (T12004) Tungsten High-Speed Steel

SAE-AISI T4 steel is a tool steel. T4 is the designation in both the SAE and AISI systems for this material. T12004 is the UNS number.

The properties of SAE-AISI T4 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 T4 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

210 GPa 30 x 106 psi

Poisson's Ratio


Shear Modulus

80 GPa 12 x 106 psi

Tensile Strength: Ultimate (UTS)

800 to 2140 MPa 120 to 310 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Melting Completion (Liquidus)

1810 °C 3280 °F

Melting Onset (Solidus)

1750 °C 3180 °F

Specific Heat Capacity

410 J/kg-K 0.1 BTU/lb-°F

Thermal Conductivity

21 W/m-K 12 BTU/h-ft-°F

Thermal Expansion

12 µm/m-K

Otherwise Unclassified Properties

Base Metal Price

55 % relative


9.4 g/cm3 580 lb/ft3

Embodied Carbon

8.5 kg CO2/kg material

Embodied Energy

130 MJ/kg 56 x 103 BTU/lb

Embodied Water

120 L/kg 14 gal/lb

Common Calculations

PREN (Pitting Resistance)


Stiffness to Weight: Axial

12 points

Stiffness to Weight: Bending

21 points

Strength to Weight: Axial

24 to 64 points

Strength to Weight: Bending

20 to 39 points

Thermal Diffusivity

5.4 mm2/s

Thermal Shock Resistance

24 to 64 points

Alloy Composition

Iron (Fe)Fe 66.3 to 72.3
Tungsten (W)W 17.5 to 19
Cobalt (Co)Co 4.3 to 5.8
Chromium (Cr)Cr 3.8 to 4.5
Vanadium (V)V 0.8 to 1.2
Carbon (C)C 0.7 to 0.8
Molybdenum (Mo)Mo 0.4 to 1.0
Silicon (Si)Si 0.2 to 0.4
Manganese (Mn)Mn 0.1 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

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

Followup Questions

Similar Alloys

Further Reading

SAE J437: Selection and Heat Treatment of Tool and Die Steels

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