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Hardened O7 Tool Steel

Hardened SAE-AISI O7 is SAE-AISI O7 steel in the hardened (H) condition. The graph bars on the material properties cards below compare hardened SAE-AISI O7 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

65

Shear Modulus

73 GPa 11 x 106 psi

Tensile Strength: Ultimate (UTS)

2110 MPa 310 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 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

41 W/m-K 24 BTU/h-ft-°F

Thermal Expansion

12 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.6 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.7 % IACS

Otherwise Unclassified Properties

Base Metal Price

6.0 % relative

Density

7.9 g/cm3 490 lb/ft3

Embodied Carbon

2.3 kg CO2/kg material

Embodied Energy

33 MJ/kg 14 x 103 BTU/lb

Embodied Water

52 L/kg 6.2 gal/lb

Common Calculations

PREN (Pitting Resistance)

3.6

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

74 points

Strength to Weight: Bending

46 points

Thermal Diffusivity

11 mm2/s

Thermal Shock Resistance

70 points

Alloy Composition

Iron (Fe) 92.9 to 97.6
Tungsten (W) 1.0 to 2.0
Carbon (C) 1.1 to 1.3
Chromium (Cr) 0.35 to 0.85
Manganese (Mn) 0 to 1.0
Silicon (Si) 0 to 0.6
Vanadium (V) 0 to 0.4
Nickel (Ni) 0 to 0.3
Molybdenum (Mo) 0 to 0.3
Copper (Cu) 0 to 0.25
Phosphorus (P) 0 to 0.030
Sulfur (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