D2 Tool Steel - High-Carbon, High-Chromium, Cold-Work Steel (UNS T30402)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
     Heat Treatment
     Forging
     Annealing
     Tempering
Applications

Introduction

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 1.40 – 1.60
Mn 0.60
Si 0.60
Co 1.00
Cr 11.00 – 13.00
Mo 0.70 – 1.20
V 1.10
P 0.03
Ni 0.30
Cu 0.25
S 0.03

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

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

Thermal Properties

The following table shows the thermal properties of D2 steels.

Properties Conditions
T (°C) Treatment
Thermal expansion 10.4 x 10-6/ºC 20-100 -

Other Designations

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Equivalent materials to D2 tool steels are:

  • DIN 1.2379
  • NI KU
  • B.S. BD 2
  • ASTM A681
  • FED QQ-T-570
  • SAE J437
  • SAE J438
  • UNS T30402

Fabrication and Heat Treatment

Heat Treatment

D2 steels should be preheated very slowly to 815ºC (1500ºF) and then temperature can be increased to 1010ºC (1850ºF). They are then held at 1010ºC (1850ºF) for 20 to 45 minutes and air cooled (air quenched).

Forging

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

Annealing

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.

Tempering

D2 steels can be tempered at 204ºC (400ºF) for achieving Rockwell C hardness of 61 and at 537ºC (1000ºF) for a Rockwell C hardness of 54.

Applications

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.

Comments

  1. Hiren Patel Hiren Patel India says:

    How to demagnetize D2 material?

  2. mahesh raja mahesh raja India says:

    sir what is the value of coefficient of friction value of D2 HCHCr steel?

  3. Ammad Khan Ammad Khan Islamic Republic of Pakistan says:

    I want the material that contains these elements
    v 1.61
    cr 3.87
    fe 80.57
    mo 7.52
    w 6.43

The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of AZoM.com.

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