Jun 18 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Fabrication and Heat treatment
Forging
Annealing
Stress Relieving
Hardening
Tempering
Applications
Introduction
The AISI grades of tool steels are the most common scale used to identify various grades of tool steel. The higher carbon grade tool steels are typically used for applications such as stamping dies, metal cutting tools, etc.
AISI D7 tool steel is a high-carbon, high-chromium air-hardening tool steel that exhibits exceptional wear resistance, with added carbon and vanadium.
The data below will provide an overview of grade D7 tool steels.
Chemical Composition
The chemical composition of D7 tool steels is outlined in the following table.
|
Element |
Content (%) |
|
Iron, Fe |
79.3 |
|
Chromium, Cr |
12.5 |
|
Vanadium, V |
4 |
|
Carbon, C |
2.3 |
|
Molybdenum, Mo |
1.1 |
|
Silicon, Si |
0.4 |
|
Manganese, Mn |
0.4 |
Physical Properties
The following table shows the physical properties of D7 tool steels.
|
Properties |
Metric |
Imperial |
|
Density |
7.7-8.03 g/cm3 |
0.278 – 0.290 lb/in3 |
Mechanical Properties
The mechanical properties of D7 tool steels are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Modulus of elasticity |
190-210 GPa |
27557-30458 ksi |
|
Poisson’s ratio |
0.27-0.30 |
0.27-0.30 |
|
Hardness, Rockwell C |
62.5 |
62.5 |
|
Izod impact unnotched |
21.7 J |
16 ft.lb |
Fabrication and Heat treatment
Forging
D7 tool steel is slowly heated at 1093 - 1149°C (2050 - 2100°F). The forgings are then cooled slowly in dry sand or in other insulating media.
Annealing
D7 tool steel is heated at 871 - 899°C (1600 -1650°F) for 2 hours and cooled to 538°C (1000°F).
Stress Relieving
To relieve machining stresses, A11 tool steels are heated to a temperature of 621 - 677°C (1150 - 1300°F) and then slowly cooled in still air.
Hardening
D7 tool steel is hardened at (1900-2000°F) and slowly cooled in air.
Tempering
Tempering of D7 tool steel is carried out at (400-1000°F) for 1 h.
Applications
The following are the list of applications of D7 tool steels:
-
Brick mold liners
-
Powder compaction tooling
-
Shot blasting equipment liners
-
Flattening rolls
-
Powder compaction tooling
-
Tools for ceramic extrusion and molding.