Materials / Compare
Iron vs. Nickel Inconel 718
Compare Iron vs. Nickel Inconel 718 strength, stiffness, weight and thermal properties.
| Try it on a partA bracket to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | 186MPasourcetypical (0.2% YS), hot rolled + SRA/recrystallization anneal | 1,207MPasourcetypical, 1.0 in. hot-rolled bar, 0.2% offset |
| Ultimate tensile strength | 290MPasourcetypical, SRA/recrystallization anneal | 1,389MPasourcetypical, 1.0 in. bar |
| Elongation at break | 38%sourcetypical, gauge 4D0 | 20%sourcetypical, 1.0 in. bar |
| Young's modulus (stiffness) | 207GPasourcetypical, after SRA/recrystallization anneal | 200GPasourcetypical, 21 °C, annealed + aged |
| Density | 7,860kg/m³sourcetypical | 8,221kg/m³sourcenominal, annealed and aged |
| Strength to weight | 23.7kN·m/kg | 147kN·m/kg6.2x higher |
| Stiffness to weight | 26.3MN·m/kg8% higher | 24.3MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | 0.294sourcetypical, 21 °C, annealed + aged |
| Shear modulus | 80.7GPa4% stiffer in shear | 77.3GPa |
| Bulk modulus | 158GPa | 162GPa |
| Speed of sound | 5,132m/s | 4,932m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a) |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged |
| 100 mm part over a 50 °C swing | 68.5µm growth | 66µm growth4% less |
| Specific heat | 450J/kg·Ksourcetypical | 435J/kg·Ksourcetypical, 21 °C |
| Heats up and cools (diffusivity) | 20.7mm²/s6.49x faster | 3.19mm²/s |
| Thermal shock resistance | 3,447W/m | 3,680W/m7% more resistant |
| Melting point | 1,532°Csourcetypical | 1,260–1,336°Csourcemelting range |
| Max service temperature | not sourced | 704°Csourceupper use temperature stated by producer |
| Values for | Cleveland-Cliffs / AK Steel ARMCO Pure Iron Product Data Bulletin (07/2022): Table 1 typical physical properties, Table 2 typical mechanical properties after SRA/recrystallization anneal. | INCONEL alloy 718, standard grade, 1750 °F/1 hr anneal + 1325 °F/8 hr F.C. to 1150 °F aged; Special Metals bulletin SMC-045 typical values |
Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
Questions
Is Iron stronger than Nickel Inconel 718?
Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 186 MPa for Iron (6.49x).
Which is lighter, Iron or Nickel Inconel 718?
Iron is lighter: 7,860 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.
Which is stiffer, Iron or Nickel Inconel 718?
Iron is stiffer: Young's modulus 207 GPa against 200 GPa for Nickel Inconel 718, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Nickel Inconel 718?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Nickel Inconel 718 is lighter for a strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | Nickel Inconel 718 |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 8% heavier |
| Stiff beam (bending) | lighter | 6% heavier |
| Stiff panel or plate | lighter | 6% heavier |
| Strong rod or tie | 6.2x heavier | lighter |
| Strong beam | 3.33x heavier | lighter |
| Strong panel or plate | 2.44x heavier | lighter |
For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).
Which conducts heat better, Iron or Nickel Inconel 718?
Iron conducts heat better: 73.2 W/m·K against 11.4 W/m·K for Nickel Inconel 718.
Which expands less with temperature?
Nickel Inconel 718 expands less: 13.2 µm/m·K against 13.7 µm/m·K for Iron.