Hardened T8 Tool Steel
Hardened SAE-AISI T8 is SAE-AISI T8 steel in the hardened (H) condition. The graph bars on the material properties cards below compare hardened SAE-AISI T8 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
200 GPa 29 x 106 psi
Poisson's Ratio
0.29
Rockwell C Hardness
66
Shear Modulus
78 GPa 11 x 106 psi
Tensile Strength: Ultimate (UTS)
2140 MPa 310 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Melting Completion (Liquidus)
1730 °C 3140 °F
Melting Onset (Solidus)
1670 °C 3050 °F
Specific Heat Capacity
420 J/kg-K 0.1 BTU/lb-°F
Thermal Conductivity
18 W/m-K 11 BTU/h-ft-°F
Thermal Expansion
12 µm/m-K
Otherwise Unclassified Properties
Base Metal Price
45 % relative
Density
9.0 g/cm3 560 lb/ft3
Embodied Carbon
10 kg CO2/kg material
Embodied Energy
160 MJ/kg 67 x 103 BTU/lb
Embodied Water
120 L/kg 14 gal/lb
Common Calculations
PREN (Pitting Resistance)
30
Stiffness to Weight: Axial
12 points
Stiffness to Weight: Bending
22 points
Strength to Weight: Axial
66 points
Strength to Weight: Bending
41 points
Thermal Diffusivity
4.8 mm2/s
Thermal Shock Resistance
66 points
Alloy Composition
| Fe | 69.3 to 75.4 | |
| W | 13.3 to 14.8 | |
| Co | 4.3 to 5.8 | |
| Cr | 3.8 to 4.5 | |
| V | 1.8 to 2.4 | |
| C | 0.75 to 0.85 | |
| Mo | 0.4 to 1.0 | |
| Mn | 0.2 to 0.4 | |
| Si | 0.2 to 0.4 | |
| Ni | 0 to 0.3 | |
| Cu | 0 to 0.25 | |
| P | 0 to 0.030 | |
| S | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Further Reading
SAE J437: Selection and Heat Treatment of Tool and Die Steels
ASTM A600: Standard Specification for Tool Steel High Speed
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