SAE-AISI 4720 (G47200) Ni-Cr-Mo Steel
SAE-AISI 4720 steel is an alloy steel formulated for primary forming into wrought products. Cited properties are appropriate for the annealed condition. 4720 is the designation in both the SAE and AISI systems for this material. G47200 is the UNS number.
The graph bars on the material properties cards below compare SAE-AISI 4720 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
Elastic (Young's, Tensile) Modulus
190 GPa 27 x 106 psi
Elongation at Break
25 %
Fatigue Strength
260 MPa 37 x 103 psi
Poisson's Ratio
0.29
Shear Modulus
73 GPa 11 x 106 psi
Shear Strength
310 MPa 46 x 103 psi
Tensile Strength: Ultimate (UTS)
490 MPa 71 x 103 psi
Tensile Strength: Yield (Proof)
350 MPa 51 x 103 psi
Thermal Properties
Latent Heat of Fusion
250 J/g
Maximum Temperature: Mechanical
410 °C 780 °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
39 W/m-K 22 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
2.9 % relative
Density
7.9 g/cm3 490 lb/ft3
Embodied Carbon
1.6 kg CO2/kg material
Embodied Energy
21 MJ/kg 8.9 x 103 BTU/lb
Embodied Water
50 L/kg 6.0 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
110 MJ/m3
Resilience: Unit (Modulus of Resilience)
330 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
24 points
Strength to Weight: Axial
17 points
Strength to Weight: Bending
18 points
Thermal Diffusivity
10 mm2/s
Thermal Shock Resistance
14 points
Alloy Composition
Among alloy steels, the composition of SAE-AISI 4720 steel is notable for including nickel (Ni). Nickel is used to improve mechanical properties, and to make the alloy easier to heat treat.
| Fe | 96.7 to 97.8 | |
| Ni | 0.9 to 1.2 | |
| Mn | 0.5 to 0.7 | |
| Cr | 0.35 to 0.55 | |
| Si | 0.15 to 0.35 | |
| Mo | 0.15 to 0.25 | |
| C | 0.17 to 0.22 | |
| 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
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
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015
Steels: Processing, Structure, and Performance, 2nd ed., George Krauss, 2015