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Hardened A8 Tool Steel

Hardened SAE-AISI A8 is SAE-AISI A8 steel in the hardened (H) condition. The graph bars on the material properties cards below compare hardened SAE-AISI A8 to: tool steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Elastic (Young's, Tensile) Modulus

190 GPa 28 x 106 psi

Poisson's Ratio

0.29

Rockwell C Hardness

59

Shear Modulus

74 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

1920 MPa 280 x 103 psi

Thermal Properties

Latent Heat of Fusion

270 J/g

Melting Completion (Liquidus)

1480 °C 2690 °F

Melting Onset (Solidus)

1430 °C 2610 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

37 W/m-K 21 BTU/h-ft-°F

Thermal Expansion

12 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

8.3 % IACS

Electrical Conductivity: Equal Weight (Specific)

9.5 % IACS

Otherwise Unclassified Properties

Base Metal Price

8.5 % relative

Density

7.9 g/cm3 490 lb/ft3

Embodied Carbon

2.3 kg CO2/kg material

Embodied Energy

31 MJ/kg 13 x 103 BTU/lb

Embodied Water

73 L/kg 8.8 gal/lb

Common Calculations

PREN (Pitting Resistance)

12

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

68 points

Strength to Weight: Bending

44 points

Thermal Diffusivity

9.9 mm2/s

Thermal Shock Resistance

62 points

Alloy Composition

Iron (Fe)Fe 88.5 to 91.9
Chromium (Cr)Cr 4.8 to 5.5
Molybdenum (Mo)Mo 1.2 to 1.7
Tungsten (W)W 1.0 to 1.5
Silicon (Si)Si 0.75 to 1.1
Carbon (C)C 0.5 to 0.6
Manganese (Mn)Mn 0 to 0.5
Nickel (Ni)Ni 0 to 0.3
Copper (Cu)Cu 0 to 0.25
Phosphorus (P)P 0 to 0.030
Sulfur (S)S 0 to 0.030

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Further Reading

ASTM A681: Standard Specification for Tool Steels Alloy

Tool Steels, 5th ed., George Roberts et al., 1998

Tool Steels: Properties and Performance, Rafael A. Mesquita (editor), 2016

ASM Specialty Handbook: Carbon and Alloy Steels, J. R. Davis (editor), 1996