SAE-AISI O2 (T31502) Oil-Hardening Steel
SAE-AISI O2 steel is a tool steel. O2 is the designation in both the SAE and AISI systems for this material. T31502 is the UNS number.
The properties of SAE-AISI O2 steel include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare SAE-AISI O2 steel 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
Shear Modulus
72 GPa 10 x 106 psi
Tensile Strength: Ultimate (UTS)
640 to 2050 MPa 93 to 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
43 W/m-K 25 BTU/h-ft-°F
Thermal Expansion
11 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
2.4 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.8 kg CO2/kg material
Embodied Energy
26 MJ/kg 11 x 103 BTU/lb
Embodied Water
50 L/kg 6.0 gal/lb
Common Calculations
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
23 to 73 points
Strength to Weight: Bending
21 to 46 points
Thermal Diffusivity
12 mm2/s
Thermal Shock Resistance
22 to 70 points
Alloy Composition
| Fe | 95 to 97.8 | |
| Mn | 1.4 to 1.8 | |
| C | 0.85 to 1.0 | |
| Si | 0 to 0.5 | |
| Cr | 0 to 0.5 | |
| Ni | 0 to 0.3 | |
| Mo | 0 to 0.3 | |
| V | 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
Similar Alloys
Further Reading
SAE J437: Selection and Heat Treatment of Tool and Die Steels
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
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015