Sep 18 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesThermal PropertiesOther Designations
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. All group D steels include 1% Mo and are air hardened except for type D3 steel. Type D3 steel is oil-quenched; though small sections can be gas quenched after austenitization using vacuum. Consequently, tools made with type D3 steel tend to be brittle during hardening. Type D2 steel is the most commonly used steel among the group D steels.
The following section will discuss more about D4 type of tool steels.
Chemical Composition
The chemical composition of D4 tool steels is given below:
| Element |
Content (%) |
| C |
2.05 – 2.40 |
| Mn |
0.60 |
| Si |
0.60 |
| Cr |
11.00 – 13.00 |
| Ni |
0.30 |
| Mo |
0.70-1.20 |
| V |
1.00 |
| P |
0.03 |
| S |
0.03 |
| Cu |
0.25 |
Physical Properties
Following are the physical properties of D4 tool steels.
| Physical Properties |
Metric |
Imperial |
| Density |
7.7 x 1000 kg/m3 |
0.278 lb/in3 |
Mechanical Properties
The mechanical properties of D4 steels are tabulated below:
| Mechanical Properties |
Metric |
Imperial |
| 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 D4 steels.
| Properties |
Conditions |
| T (°C) |
Treatment |
| Thermal expansion |
12.4 x 10-6/ºC |
20-100 |
- |
Other Designations
The metals that are equivalent to D4 steel are:
- ASTM A681
- FED QQ-T-570
- UNS T30404