Jun 18 2013
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
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.