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
| Fe | 92 to 95.5 | |
| Mn | 1.8 to 2.2 | |
| Cr | 0.9 to 2.2 | |
| Mo | 0.9 to 1.4 | |
| C | 1.0 to 1.1 | |
| Si | 0 to 0.5 | |
| 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
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