A10 Tool Steel - Air-Hardening, Medium-Alloy, Cold-Work Steels (UNS T30110)

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 of 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.

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 at 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.

Comments

  1. Joe Smith Joe Smith United States says:

    This might be silly, but i would like to know which of the airhards might make good knives. A2 and D2 are classic knife steels and I'm told A6 isn't bad.

    For the application i have in mind a steel would have to have these qualifications: forgeable, does NOT need a long soak at hardening temp, does NOT need a long tempering period produces a reasonably tough blade at around RC58. Ideally, it would harden to 58 or so and not even need tempering but that might be too much to ask for.

    very truly your, joe the blacksmith

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