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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.

Iron (Fe) 97.4 to 98.2
Manganese (Mn) 0.75 to 1.0
Carbon (C) 0.48 to 0.53
Chromium (Cr) 0.4 to 0.6
Silicon (Si) 0.15 to 0.35
Sulfur (S) 0 to 0.040
Phosphorus (P) 0 to 0.035
Boron (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