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SAE-AISI 4024 (G40240) Molybdenum Steel

SAE-AISI 4024 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the cold worked (strain hardened) condition. 4024 is the designation in both the SAE and AISI systems for this material. G40240 is the UNS number.

It has a moderately high thermal conductivity and a moderately low ductility among SAE-AISI wrought steels.

The graph bars on the material properties cards below compare SAE-AISI 4024 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

14 %

Fatigue Strength

320 MPa 46 x 103 psi

Poisson's Ratio

0.29

Shear Modulus

73 GPa 11 x 106 psi

Shear Strength

370 MPa 53 x 103 psi

Tensile Strength: Ultimate (UTS)

600 MPa 87 x 103 psi

Tensile Strength: Yield (Proof)

500 MPa 73 x 103 psi

Thermal Properties

Latent Heat of Fusion

250 J/g

Maximum Temperature: Mechanical

400 °C 760 °F

Melting Completion (Liquidus)

1460 °C 2660 °F

Melting Onset (Solidus)

1420 °C 2590 °F

Specific Heat Capacity

470 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

51 W/m-K 29 BTU/h-ft-°F

Thermal Expansion

13 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

7.1 % IACS

Electrical Conductivity: Equal Weight (Specific)

8.1 % IACS

Otherwise Unclassified Properties

Base Metal Price

2.1 % relative

Density

7.8 g/cm3 490 lb/ft3

Embodied Carbon

1.5 kg CO2/kg material

Embodied Energy

19 MJ/kg 8.3 x 103 BTU/lb

Embodied Water

47 L/kg 5.6 gal/lb

Common Calculations

Resilience: Ultimate (Unit Rupture Work)

77 MJ/m3

Resilience: Unit (Modulus of Resilience)

670 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

14 mm2/s

Thermal Shock Resistance

18 points

Alloy Composition

Among alloy steels, the composition of SAE-AISI 4024 steel is notable for containing comparatively high amounts of manganese (Mn) and silicon (Si). Manganese is used to improve hardenability, hot workability, and surface quality. There is some loss of ductility and weldability, however. Silicon content is typically governed by metallurgical processing concerns, and not its effects on final material properties. However, it does have a modest strengthening effect.

Iron (Fe) 98.1 to 98.7
Manganese (Mn) 0.7 to 0.9
Silicon (Si) 0.15 to 0.35
Molybdenum (Mo) 0.2 to 0.3
Carbon (C) 0.2 to 0.25
Sulfur (S) 0.035 to 0.050
Phosphorus (P) 0 to 0.035

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM A322: Standard Specification for Steel Bars, Alloy, Standard Grades

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