Materials / Compare
Nickel Inconel 718 vs. Stainless 304
Compare Nickel Inconel 718 vs. Stainless 304 strength, stiffness, weight and thermal properties.
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|---|---|---|
| Mechanical | ||
| Yield strength | 1,207MPasourcetypical, 1.0 in. hot-rolled bar, 0.2% offset | 241MPasourcetypical, annealed, 70 °F (21 °C) |
| Ultimate tensile strength | 1,389MPasourcetypical, 1.0 in. bar | 586MPasourcetypical, annealed, 70 °F (21 °C) |
| Elongation at break | 20%sourcetypical, 1.0 in. bar | 55%sourcetypical, annealed, in 2 in. (50.8 mm) |
| Young's modulus (stiffness) | 200GPasourcetypical, 21 °C, annealed + aged | 193GPasourcetypical, in tension |
| Density | 8,221kg/m³sourcenominal, annealed and aged | 8,030kg/m³sourcetypical |
| Strength to weight | 147kN·m/kg4.89x higher | 30kN·m/kg |
| Stiffness to weight | 24.3MN·m/kg1% higher | 24MN·m/kg |
| Poisson's ratio | 0.294sourcetypical, 21 °C, annealed + aged | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 77.3GPa4% stiffer in shear | 74.2GPa |
| Bulk modulus | 162GPa | 161GPa |
| Speed of sound | 4,932m/s | 4,903m/s |
| Thermal | ||
| Thermal conductivity | 11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a) | 16.2W/m·Ksourceat 100 °C |
| Thermal expansion | 13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged | 16.9µm/m·Ksourcemean, 0–100 °C |
| 100 mm part over a 50 °C swing | 66µm growth28% less | 84.5µm growth |
| Specific heat | 435J/kg·Ksourcetypical, 21 °C | 500J/kg·Ksourcemean, 0–100 °C |
| Heats up and cools (diffusivity) | 3.19mm²/s | 4.03mm²/s27% faster |
| Thermal shock resistance | 3,680W/m4.39x more resistant | 838W/m |
| Melting point | 1,260–1,336°Csourcemelting range | 1,399–1,454°Csourcemelting range |
| Max service temperature | 704°Csourceupper use temperature stated by producer | 899°Csourcecontinuous, oxidation (scaling) limit in air |
| Values for | 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 | Type 304, annealed flat-rolled (Cleveland-Cliffs 304/304L Product Data Bulletin, May 2021); Poisson's ratio from the Nickel Institute/SCI structural stainless design manual |
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 Nickel Inconel 718 stronger than Stainless 304?
Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 241 MPa for Stainless 304 (5.01x).
Which is lighter, Nickel Inconel 718 or Stainless 304?
Stainless 304 is lighter: 8,030 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.
Which is stiffer, Nickel Inconel 718 or Stainless 304?
Nickel Inconel 718 is stiffer: Young's modulus 200 GPa against 193 GPa for Stainless 304, so the same part in Nickel Inconel 718 deflects less under the same load.
Which is lighter for the same job, Nickel Inconel 718 or Stainless 304?
For the same stiffness or strength: Nickel Inconel 718 is lighter for a stiff rod or tie (tension), strong rod or tie, strong beam, strong panel or plate; Stainless 304 is lighter for a stiff panel or plate.
| Part that must be | Nickel Inconel 718 | Stainless 304 |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 1% heavier |
| Stiff beam (bending) | about equal | about equal |
| Stiff panel or plate | 1% heavier | lighter |
| Strong rod or tie | lighter | 4.89x heavier |
| Strong beam | lighter | 2.86x heavier |
| Strong panel or plate | lighter | 2.19x heavier |
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, Nickel Inconel 718 or Stainless 304?
Stainless 304 conducts heat better: 16.2 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 16.9 µm/m·K for Stainless 304.