T15 Tool Steel (UNS T12015) - Tungsten High Speed Steel

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations


Tungsten is a good carbide former that increases temperature and red hardness, prevents gain growth and improves toughness. It is a steel gray metal used in high speed steels and hot forming tool steels.

Tungsten high speed tool steels or group T steels range from T1 to T15 steels. This article on the tool steel type T15 will focus on the chemical composition, physical, mechanical, and thermal properties, and other designations of T15 tool steels.

Chemical Composition

The chemical composition of T15 tool steels is outlined in the following table.

Element Content (%)
Tungsten, W 11.75-13
Cobalt, Co 4.75-5.25
Vanadium, V 4.50-5.25
Chromium, Cr 3.75-5
Carbon, C 1.50-1.60
Molybdenum, Mo 1 (max)
Nickel, Ni 0.3
Copper, Cu 0.25
Manganese, Mn 0.15-0.40
Silicon, Si 0.15-0.40
Phosphorus, P 0.03
Sulfur, S 0.03

Physical Properties

The table below shows the physical properties of T15 tool steels.

Properties Metric Imperial
Density 8.19 g/cm3 0.295 lb/in3

Mechanical Properties

The mechanical properties of T15 tool steels are displayed in the following table.

Properties Metric Imperial
Poisson's ratio 0.27-0.30 0.27-0.30
Elastic modulus 190-210 GPa 27557-30457 Ksi
Izod impact unnotched 27.1 - 46.1 J 20.0 - 34.0 ft.lb
Abrasion (loss in mm3, tempered at 1025°F; ASTM G65 ) 8 8
Abrasion (loss in mm3, tempered at 1275°F; ASTM G65 ) 32.3 32.3
Hardness, Rockwell C (tempered at 1275°F) 46.5 46.5
Hardness, Rockwell C (tempered at 1025°F) 67.5 67.5

Thermal Properties

The table below outlines the thermal properties of T15 tool steels.

Properties Conditions
T (ºC) Treatment
Thermal expansion 9.9 x 10-6/ºC 20-200 -
Thermal conductivity 20.9 x W/m-K 100 -

Other Designations

Equivalent materials to T15 tool steels are:

  • DIN 1.3202
  • UNI 130505 KU
  • B.S. BT 15
  • ASTM A600
  • FED QQ-T-590
  • UNS T12001
  • UNS T12015
  • DIN 1.3202

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