Topics CoveredIntroductionChemical CompositionPhysical PropertiesMechanical PropertiesThermal PropertiesOther Designations
Steels of the type A2, A3, A4, A6, A7, A8, A9, and A10 are called air-hardening, medium alloy, cold work steels or group A 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.
The carbon content group A steels range from 0.5 to 2%. These steels are provided with air hardening characteristics that allow minimum cracking and distortion on quenching.
The data below will provide an overview of A6 air-hardening, medium-alloy, cold-work tool steels.
The chemical composition of A6 tool steels is outlined in the following table.
The following table shows the physical properties of A6 tool steels.
The mechanical properties of A6 tool steels are displayed in the following table.
|Hardness, Rockwell C (as air quenched from 845°C, tempered for 2 hours. 61-62 HRC at 95°C temper, 60-61 HRC at 150°C temper, 58-59 HRC at 205°C temper, 56-57 HRC at 260°C temper, 55-56 HRC at 315°C temper, 52-53 HRC at 425°C temper, 50-51 HRC at 480°C temper, 48-49 HRC at 540°C temper)
|Bulk modulus (typical for steels)
|Machinability (based on carbon tool steel)
|Shear modulus (estimated from elastic modulus)
The thermal properties of A6 tool steels are given in the following table.
||11.5 x 10-6/ºC
Equivalent materials to A2 tool steels are:
- ASTM A68i
- FED QQ-T-570
- UNS T30i06
- ASTM A681 (A-6)
- UNS T30106