Grade D6 Tool Steel (UNS T30406)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat treatment
     Forging
     Annealing
     Stress Relieving
     Hardening
     Tempering
Applications

Introduction

Tool steels are primarily used to manufacture tools that can be used for machining metals, woods, and plastics. They are generally ingot-cast wrought products, and have the potential to be stable at elevated temperatures and withstand high specific loads.

AISI D6 tool steel is a high-carbon, high chromium tool steel alloyed with tungsten that is characterized by high compressive strength, high wear resistance, high surface hardness and good hardening stability.

The data below will provide an overview of grade D6 tool steels.

Chemical Composition

The chemical composition of D6 tool steels is outlined in the following table.

Element Content (%)
Iron, Fe 83.05
Chromium, Cr 12.5
Carbon, C 2.05
Tungsten, W 1.3
Manganese, Mn 0.8
Silicon, Si 0.3

Physical Properties

The following table shows the physical properties of D6 tool steels.

Properties Metric Imperial
Density 7.67 g/cm3 0.277 lb/in3

Mechanical Properties

The mechanical properties of D6 tool steels are displayed in the following table.

Properties Metric Imperial
Compressive strength 1320 MPa 191000 psi
Modulus of elasticity 194 GPa 28100 ksi
Hardness, Rockwell C 46 46

Thermal Properties

The thermal properties of D6 tool steels are given in the following table

Properties Metric Imperial
Thermal expansion co-efficient (@21-400°C/68-752°F) 10.8 µm/m°C 6 µin/in°F
Thermal conductivity (@20°C/68°F) 20.5 W/mK 142 BTU.in/hrft².°F

Fabrication and Heat treatment

Forging

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D6 tool steel is heated slowly and uniformly to 700°C (1292°F) and then more rapidly to 900-1050°C (1652-1922°F).

Annealing

D6 tool steel is then annealed at 800-840°C (1472-1544°F) and cooled. Hardness of the steel after annealing will be approximately 225 Brinell.

Stress Relieving

Stresses from D6 tool steel can be eliminated before hardening by heating up to 650-700°C (1202-1292°F), if machining operations have been heavy. The steel is then allowed to cool slowly.

Hardening

D6 steel is pre-heated slowly to 750-800°C (1382-1472°F) and thoroughly soaked. Heating is then continued till the final hardening of 950-980°C (1742-1796°F), followed by air or oil quenching.

Tempering

The steel is heated uniformly and thoroughly at the selected tempering temperature. Double tempering can also be carried out with intermediate cooling to room temperature.

Applications

The following are the list of applications of D6 tool steels:

  • Forming tools
  • Molds for abrasive plastics and ceramics
  • Long-run press tools
  • Blanking and shearing tools for hard materials.

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