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Hardened A4 Tool Steel

Hardened SAE-AISI A4 is SAE-AISI A4 steel in the hardened (H) condition. The graph bars on the material properties cards below compare hardened SAE-AISI A4 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 27 x 106 psi

Poisson's Ratio

0.29

Rockwell C Hardness

63

Shear Modulus

73 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

2050 MPa 300 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Melting Completion (Liquidus)

1450 °C 2640 °F

Melting Onset (Solidus)

1410 °C 2570 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

40 W/m-K 23 BTU/h-ft-°F

Thermal Expansion

12 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.4 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.6 % IACS

Otherwise Unclassified Properties

Base Metal Price

3.9 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

1.8 kg CO2/kg material

Embodied Energy

24 MJ/kg 10 x 103 BTU/lb

Embodied Water

59 L/kg 7.0 gal/lb

Common Calculations

PREN (Pitting Resistance)

5.3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

73 points

Strength to Weight: Bending

46 points

Thermal Diffusivity

11 mm2/s

Thermal Shock Resistance

67 points

Alloy Composition

Iron (Fe)Fe 92 to 95.5
Manganese (Mn)Mn 1.8 to 2.2
Chromium (Cr)Cr 0.9 to 2.2
Molybdenum (Mo)Mo 0.9 to 1.4
Carbon (C)C 1.0 to 1.1
Silicon (Si)Si 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