D2 / KNL

 D2 / KNL | DIN 1.2601 | X165CrMoV12 | B.S. BD 2 | ASTM A681 | FED QQ-T-570 | K 105 | SAE J438 | UNS T30402

Cold-work tool steels include the high-carbon, high-chromium steels or group D steels. These steels are designated as group D steels and consist of D2, D3, D4, D5, and D7 steels. These steels contain 1.5 to 2.35% of carbon and 12% of chromium. Except type D3 steel, all the other group D steels include 1% Mo and are air hardened. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using vacuum. As a result, tools made with type D3 steel tends to be brittle during hardening. Type D2 steel is the most commonly used steel among the group D steels.

Chemical Composition

The following table shows the chemical composition of D2 tool steels.

Element Content (%)
C 1.55-1.75
Mn 0.20-0.40
Si 0.25-0.40
P 0.030 max
Cr 11.00-12.00
Mo 0.50-0.70
V 0.10-0.50
S 0.030 max
w 0.40-0.60

Mechanical Properties

The mechanical properties of D2 steels are tabulated below:

Mechanical Properties Metric Imperial
Hardness, Knoop (converted from Rockwell C hardness) 769 769
Hardness, Rockwell C 62 62
Hardness, Vickers 748 748
Izod impact unnotched 77.0 J 56.8 ft-lb
Poisson’s ratio 0.27-0.30 0.27-0.30
Elastic modulus 190-210 GPa 27557-30457 ksi

Physical Properties

The physical properties of D2 tool steels are outlined in the following table.

Properties Metric Imperial
Density 7.7 x 1000 kg/m3 0.278 lb/in3
Melting point 1421°C 2590°F


Forging of D2 steels can be done from 1065ºC (1950ºF) down to 954ºC (1750ºF). Do not forge below 926ºC (1700ºF).


Annealing of D2 steels should be done at 871 to 898ºC (1600 to 1650ºF) followed by slow furnace cooling at 4.4ºC (40ºF) per hour or less.


D2 tool steels are used for long run tooling applications, where wear resistance is important, such as blanking or forming dies and thread rolling dies.


  • DIN 1.2601
  • X165CrMoV12
  • B.S. BD 2
  • ASTM A681
  • FED QQ-T-570
  • K 105
  • SAE J438
  • UNS T30402


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