SAE-AISI 50B50 (G50501) Boron Steel
SAE-AISI 50B50 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. 50B50 is the designation in both the SAE and AISI systems for this material. G50501 is the UNS number.
It has a moderately low base cost among the SAE-AISI wrought steels in the database.
The graph bars on the material properties cards below compare SAE-AISI 50B50 steel 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
180
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
22 %
Fatigue Strength
260 MPa 38 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
370 MPa 54 x 103 psi
Tensile Strength: Ultimate (UTS)
590 MPa 86 x 103 psi
Tensile Strength: Yield (Proof)
370 MPa 54 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)
1410 °C 2580 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
45 W/m-K 26 BTU/h-ft-°F
Thermal Expansion
13 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
2.0 % relative
Density
7.8 g/cm3 490 lb/ft3
Embodied Carbon
1.4 kg CO2/kg material
Embodied Energy
19 MJ/kg 8.2 x 103 BTU/lb
Embodied Water
48 L/kg 5.8 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
110 MJ/m3
Resilience: Unit (Modulus of Resilience)
370 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
21 points
Strength to Weight: Bending
20 points
Thermal Diffusivity
12 mm2/s
Thermal Shock Resistance
17 points
Alloy Composition
Among alloy steels, the composition of SAE-AISI 50B50 steel is notable for including boron (B). Boron is used to improve hardenability. It has a substantial effect when added in even tiny amounts.
| Fe | 97.4 to 98.2 | |
| Mn | 0.75 to 1.0 | |
| C | 0.48 to 0.53 | |
| Cr | 0.4 to 0.6 | |
| Si | 0.15 to 0.35 | |
| 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
Similar Alloys
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
Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993
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