Annealed 81B45 Boron Steel
Annealed SAE-AISI 81B45 is SAE-AISI 81B45 steel in the annealed condition. The graph bars on the material properties cards below compare annealed SAE-AISI 81B45 to: SAE-AISI wrought 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
Brinell Hardness
160
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
24 %
Fatigue Strength
250 MPa 36 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
340 MPa 50 x 103 psi
Tensile Strength: Ultimate (UTS)
540 MPa 79 x 103 psi
Tensile Strength: Yield (Proof)
350 MPa 50 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
410 °C 770 °F
Melting Completion (Liquidus)
1460 °C 2650 °F
Melting Onset (Solidus)
1420 °C 2580 °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
7.2 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.3 % IACS
Otherwise Unclassified Properties
Base Metal Price
2.3 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.5 kg CO2/kg material
Embodied Energy
20 MJ/kg 8.5 x 103 BTU/lb
Embodied Water
49 L/kg 5.8 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
110 MJ/m3
Resilience: Unit (Modulus of Resilience)
320 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
19 points
Strength to Weight: Bending
19 points
Thermal Diffusivity
11 mm2/s
Thermal Shock Resistance
17 points
Alloy Composition
| Fe | 97 to 98 | |
| Mn | 0.75 to 1.0 | |
| C | 0.43 to 0.48 | |
| Cr | 0.35 to 0.55 | |
| Ni | 0.2 to 0.4 | |
| Si | 0.15 to 0.35 | |
| Mo | 0.080 to 0.15 | |
| S | 0 to 0.040 | |
| P | 0 to 0.035 | |
| B | 0.00050 to 0.0030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Further Reading
ASTM A752: Standard Specification for General Requirements for Wire Rods and Coarse Round Wire, Alloy Steel
ASTM A322: Standard Specification for Steel Bars, Alloy, Standard Grades
Boron in Steel, S. K. Banerji and J. E. Morral (editors), 1980
ASTM A29: Standard Specification for Steel Bars, Carbon and Alloy, Hot-Wrought, General Requirements for
ASM Specialty Handbook: Carbon and Alloy Steels, J. R. Davis (editor), 1996
Manufacture and Uses of Alloy Steels, Henry D. Hibbard, 2005
Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015