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SAE-AISI 4028 (G40280) Molybdenum Steel

SAE-AISI 4028 steel is an alloy steel formulated for primary forming into wrought products. 4028 is the designation in both the SAE and AISI systems for this material. G40280 is the UNS number.

The properties of SAE-AISI 4028 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 4028 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

150 to 190

Elastic (Young's, Tensile) Modulus

190 GPa 27 x 106 psi

Elongation at Break

14 to 23 %

Fatigue Strength

180 to 330 MPa 27 to 48 x 103 psi

Poisson's Ratio

0.29

Shear Modulus

73 GPa 11 x 106 psi

Shear Strength

310 to 380 MPa 45 to 55 x 103 psi

Tensile Strength: Ultimate (UTS)

490 to 630 MPa 71 to 91 x 103 psi

Tensile Strength: Yield (Proof)

260 to 520 MPa 37 to 76 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

49 W/m-K 28 BTU/h-ft-°F

Thermal Expansion

12 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)

81 to 95 MJ/m3

Resilience: Unit (Modulus of Resilience)

180 to 720 kJ/m3

Stiffness to Weight: Axial

13 points

Stiffness to Weight: Bending

24 points

Strength to Weight: Axial

17 to 22 points

Strength to Weight: Bending

18 to 21 points

Thermal Diffusivity

13 mm2/s

Thermal Shock Resistance

16 to 20 points

Alloy Composition

Among alloy steels, the composition of SAE-AISI 4028 steel is notable for containing comparatively high amounts of manganese (Mn) and carbon (C). Manganese is used to improve hardenability, hot workability, and surface quality. There is some loss of ductility and weldability, however. Carbon is used to increase strength at the cost of a decrease in formability.

Iron (Fe) 98.1 to 98.7
Manganese (Mn) 0.7 to 0.9
Carbon (C) 0.25 to 0.3
Silicon (Si) 0.15 to 0.35
Molybdenum (Mo) 0.2 to 0.3
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 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

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