Grade T8 Tool Steel (UNS T12008)

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations


Tool steels are high quality steels developed with controlled chemical composition to form properties essential for working and shaping of other materials. They are normally delivered to the suppliers in the soft annealed condition, which makes it easy for the manufacturer to machine the material with cutting tool for different applications.

AISI T8 tool steel is a tungsten-cobalt-vanadium high-speed tool steel. The following datasheet will provide an overview of grade T8 tool steels.

Chemical Composition

The chemical composition of T8 tool steels is outlined in the following table.

Element Content (%)
Tungsten, W 13.25-14.75
Cobalt, Co 4.25-5.75
Chromium, Cr 3.75-4.5
Vanadium, V 1.80-2.40
Carbon, C 0.75-0.85
Molybdenum, Mo 0.4-1
Nickel, Ni 0.3
Copper, Cu 0.25
Manganese, Mn 0.2-0.4
Silicon, Si 0.2-0.4
Phosphorus, P 0.03
Sulfur, S 0.03

Physical Properties

The following table shows the physical properties of T8 tool steels.

Properties Metric Imperial
Density 8.43 g/cm3 0.267 lb/in3

Mechanical Properties

The mechanical properties of T8 tool steels are displayed in the following table.

Properties Metric Imperial
Tensile strength 1158 MPa 167.95 ksi
Elongation 15% 15%
Modulus of elasticity 190-210 GPa 27557- 30457 ksi
Poisson’s ratio 0.27-0.3 0.27-0.3

Thermal Properties

The thermal properties of T8 tool steels are given in the following table

Properties Metric Imperial
Thermal expansion co-efficient 16-17 µm/m°C 8.8-9.4 µin/in°F
Thermal conductivity 16 W/mK 110².°F

Other Designations

The equivalent materials to T8 tool steels include the following:

  • ASTM A600
  • FED QQ-T-590
  • SAE J437
  • SAE J438


The following are the list of applications of T8 tool steels:

  • Drills
  • Planer tools
  • Cutoff tools
  • Roll-turning tools
  • Lathe tools.

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