SAE-AISI 4140 (SCM440, G41400) Cr-Mo Steel
SAE-AISI 4140 steel is an alloy steel formulated for primary forming into wrought products. 4140 is the designation in both the SAE and AISI systems for this material. G41400 is the UNS number. It can have a moderately high tensile strength among the SAE-AISI wrought steels in the database.
The properties of SAE-AISI 4140 steel include four common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare SAE-AISI 4140 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
200 to 310
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
11 to 26 %
Fatigue Strength
360 to 650 MPa 53 to 94 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
410 to 660 MPa 60 to 96 x 103 psi
Tensile Strength: Ultimate (UTS)
690 to 1080 MPa 100 to 160 x 103 psi
Tensile Strength: Yield (Proof)
590 to 990 MPa 85 to 140 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
420 °C 790 °F
Melting Completion (Liquidus)
1460 °C 2660 °F
Melting Onset (Solidus)
1420 °C 2580 °F
Specific Heat Capacity
470 J/kg-K 0.11 BTU/lb-°F
Thermal Conductivity
43 W/m-K 25 BTU/h-ft-°F
Thermal Expansion
13 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
7.3 % IACS
Electrical Conductivity: Equal Weight (Specific)
8.4 % IACS
Otherwise Unclassified Properties
Base Metal Price
2.4 % 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
51 L/kg 6.1 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
74 to 180 MJ/m3
Resilience: Unit (Modulus of Resilience)
920 to 2590 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
25 to 38 points
Strength to Weight: Bending
22 to 30 points
Thermal Diffusivity
12 mm2/s
Thermal Shock Resistance
20 to 32 points
Alloy Composition
Among alloy steels, the composition of SAE-AISI 4140 steel is notable for containing comparatively high amounts of chromium (Cr) and manganese (Mn). Chromium is used to improve corrosion resistance and most mechanical properties (particularly at higher temperatures). Manganese is used to improve hardenability, hot workability, and surface quality. There is some loss of ductility and weldability, however.
| Fe | 96.8 to 97.8 | |
| Cr | 0.8 to 1.1 | |
| Mn | 0.75 to 1.0 | |
| C | 0.38 to 0.43 | |
| Si | 0.15 to 0.35 | |
| Mo | 0.15 to 0.25 | |
| S | 0 to 0.040 | |
| 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
Sintering of Advanced Materials: Fundamentals and Processes, Zhigang Zak Fang (editor), 2010
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