SAE-AISI 8637 Steel vs. SAE-AISI 4718 Steel
Both SAE-AISI 8637 steel and SAE-AISI 4718 steel are iron alloys. Both are furnished in the annealed condition. Their average alloy composition is basically identical.
For each property being compared, the top bar is SAE-AISI 8637 steel and the bottom bar is SAE-AISI 4718 steel.
Metric UnitsUS Customary Units
Mechanical Properties
| Brinell Hardness | 160 | |
| 150 |
| Elastic (Young's, Tensile) Modulus, GPa | 190 | |
| 190 |
| Elongation at Break, % | 23 | |
| 24 |
| Fatigue Strength, MPa | 260 | |
| 270 |
| Poisson's Ratio | 0.29 | |
| 0.29 |
| Shear Modulus, GPa | 73 | |
| 73 |
| Shear Strength, MPa | 340 | |
| 330 |
| Tensile Strength: Ultimate (UTS), MPa | 540 | |
| 510 |
| Tensile Strength: Yield (Proof), MPa | 360 | |
| 370 |
Thermal Properties
| Latent Heat of Fusion, J/g | 250 | |
| 250 |
| Maximum Temperature: Mechanical, °C | 410 | |
| 420 |
| 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 | 38 | |
| 39 |
| Thermal Expansion, µm/m-K | 11 | |
| 11 |
Electrical Properties
| Electrical Conductivity: Equal Volume, % IACS | 7.3 | |
| 7.3 |
| Electrical Conductivity: Equal Weight (Specific), % IACS | 8.4 | |
| 8.4 |
Otherwise Unclassified Properties
| Base Metal Price, % relative | 2.6 | |
| 3.0 |
| 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 | 50 | |
| 51 |
Common Calculations
| Resilience: Ultimate (Unit Rupture Work), MJ/m3 | 110 | |
| 110 |
| Resilience: Unit (Modulus of Resilience), kJ/m3 | 340 | |
| 360 |
| Stiffness to Weight: Axial, points | 13 | |
| 13 |
| Stiffness to Weight: Bending, points | 24 | |
| 24 |
| Strength to Weight: Axial, points | 19 | |
| 18 |
| Strength to Weight: Bending, points | 19 | |
| 18 |
| Thermal Diffusivity, mm2/s | 10 | |
| 10 |
| Thermal Shock Resistance, points | 18 | |
| 17 |
Alloy Composition
| Carbon (C), % | 0.35 to 0.4 | |
| 0.16 to 0.21 |
| Chromium (Cr), % | 0.4 to 0.6 | |
| 0.35 to 0.55 |
| Iron (Fe), % | 96.6 to 97.8 | |
| 96.3 to 97.4 |
| Manganese (Mn), % | 0.75 to 1.0 | |
| 0.7 to 0.9 |
| Molybdenum (Mo), % | 0.15 to 0.25 | |
| 0.3 to 0.4 |
| Nickel (Ni), % | 0.4 to 0.7 | |
| 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 |