SAE-AISI 4118 Steel vs. SAE-AISI 4720 Steel
Both SAE-AISI 4118 steel and SAE-AISI 4720 steel are iron alloys. Both are furnished in the annealed condition. They have a very high 99% of their average alloy composition in common.
For each property being compared, the top bar is SAE-AISI 4118 steel and the bottom bar is SAE-AISI 4720 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 150 | |
| 150 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 23 | |
| 25 |
| Fatigue Strength, MPa | 230 | |
| 260 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 73 | |
| 73 |
| Shear Strength, MPa | 320 | |
| 310 |
| Tensile Strength: Ultimate (UTS), MPa | 500 | |
| 490 |
| Tensile Strength: Yield (Proof), MPa | 320 | |
| 350 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 410 | |
| 410 |
| Melting Completion (Liquidus), °C | 1460 | |
| 1460 |
| Melting Onset (Solidus), °C | 1420 | |
| 1420 |
| Specific Heat Capacity, J/kg-K | 470 | |
| 470 |
| Thermal Conductivity, W/m-K | 46 | |
| 39 |
| Thermal Expansion, µm/m-K | 13 | |
| 13 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.2 | |
| 7.3 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.2 | |
| 8.4 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 2.3 | |
| 2.9 |
| Density, g/cm3 | 7.8 | |
| 7.9 |
| Embodied Carbon, kg CO2/kg material | 1.5 | |
| 1.6 |
| Embodied Energy, MJ/kg | 20 | |
| 21 |
| Embodied Water, L/kg | 49 | |
| 50 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 100 | |
| 110 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 280 | |
| 330 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 18 | |
| 17 |
| Strength to Weight: Bending, points | 18 | |
| 18 |
| Thermal Diffusivity, mm2/s | 13 | |
| 10 |
| Thermal Shock Resistance, points | 15 | |
| 14 |
Alloy Composition
| Carbon (C), % | 0.18 to 0.23 | |
| 0.17 to 0.22 |
| Chromium (Cr), % | 0.4 to 0.6 | |
| 0.35 to 0.55 |
| Iron (Fe), % | 97.5 to 98.4 | |
| 96.7 to 97.8 |
| Manganese (Mn), % | 0.7 to 0.9 | |
| 0.5 to 0.7 |
| Molybdenum (Mo), % | 0.2 to 0.3 | |
| 0.15 to 0.25 |
| Nickel (Ni), % | 0 | |
| 0.9 to 1.2 |
| Phosphorus (P), % | 0 to 0.035 | |
| 0 to 0.035 |
| Silicon (Si), % | 0.15 to 0.35 | |
| 0.15 to 0.35 |
| Sulfur (S), % | 0 to 0.040 | |
| 0 to 0.040 |