Sep 13 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Other Designations
Fabrication and Heat Treatment
Tempering
Annealing
Cold Working
Welding
Forging
Forming
Machinability
Heat Treatment
Applications
Introduction
Air-hardening, medium alloy, cold work steels or group A steels include the A2, A3, A4, A6, A7, A8, A9, and A10 steels. Sufficient amounts of manganese, molybdenum and chromium present in group A steels provide full hardness in sections comprising thickness of at least 100 mm (4 in.) in diameter when air cooled.
Carbon content ranging from 0.5 to 2% is available in group A steels. These steels are provided with air hardening characteristics that allow minimum cracking and distortion on quenching.
A10 air-hardening, medium-alloy, cold-work steels contain manganese, molybdenum, chromium and vanadium to perform the deep hardening process without being quenched, thus reducing the deformation level to a minimum extent during hardening of A10 steels. A10 steels have medium toughness and high wear resistance.
The sections below will provide an overview on A10 tool steels.
Chemical Composition
The chemical composition of A10 tool steels is outlined in the following table.
| Element |
Content (%) |
| C |
1.25-1.50 |
| Mn |
1.60-2.10 |
| Si |
1.00-1.50 |
| Ni |
1.55-2.05 |
| Mo |
1.25-1.75 |
| Cu |
0.25 |
| P |
0.03 |
| S |
0.03 |
Physical Properties
The following table shows the physical properties of A10 tool steels.
| Properties |
Metric |
Imperial |
| Density |
7.68 g/cm3 |
0.277 lb/in3 |
| Melting point |
1421°C |
2590°F |
Mechanical Properties
The mechanical properties of A10 tool steels are displayed in the following table.
| Properties |
Metric |
Imperial |
| Hardness, Rockwell C |
52.0-62.0 |
52.0-62.0 |
| Bulk modulus (typical for steels) |
140 GPa |
20300 ksi |
| Machinability (based on carbon tool steel) |
65% |
65% |
| Shear modulus (typical for steels) |
80.0 GPa |
11600 ksi |
| Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
| Elastic modulus |
190-210 GPa |
27557-30457 ksi |
Other Designations
Equivalent materials to A10 tool steels are:
- ASTM A681
- FED QQ-T-570
- UNS T30110
Fabrication and Heat Treatment
Tempering
A10 tool steels are tempered between 204 to 427°C (400 to 800°F), thus forming a hardness of about Rockwell C 62 for low temperature to Rockwell C 55 for the 427°C (800 F) temper.
Annealing
A10 tool steels are annealed at 774°C (1425°F) and cooled in a furnace in a very slow manner at a temperature of -3.9°C (25°F) per hour or less.
Cold Working
Conventional methods are used for cold working of A10 tool steels in the annealed condition.
Welding
A10 tool steels can be welded as they are alloy steels.
Forging
A10 tool steels are forged at 1024°C (1875°F) down to 899°C (1650°F) and forging below 871°C (1600°F) is not recommended for these steels.
Forming
Forming of A10 tools steels is performed through the hot forging and machining processes.
Machinability
A10 tool steels have medium machinability which has a rating of about 85%.
Heat Treatment
A10 tool steels are preheated at 649°C (1200°F) in a slow manner following an increase in temperature to 802°C (1475°F). They are then held for 45 to 60 minutes, removed and finally cooled in air. This same heat treatment is also used to harden the A10 tool steels.
Applications
A10 tool steels are used for a variety of complex die shapes and for thread rolling dies.