Materials / Compare
Nickel Inconel 718 vs. Stainless 316
Compare Nickel Inconel 718 vs. Stainless 316 strength, stiffness, weight and thermal properties.
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|---|---|---|
| Mechanical | ||
| Yield strength | 1,207MPasourcetypical, 1.0 in. hot-rolled bar, 0.2% offset | 265MPasourcetypical (representative), annealed 1.0 mm sheet |
| Ultimate tensile strength | 1,389MPasourcetypical, 1.0 in. bar | 583MPasourcetypical (representative), annealed 1.0 mm sheet |
| Elongation at break | 20%sourcetypical, 1.0 in. bar | 61%sourcetypical (representative), annealed, in 2 in. (51 mm) |
| Young's modulus (stiffness) | 200GPasourcetypical, 21 °C, annealed + aged | 200GPasourcetypical, in tension |
| Density | 8,221kg/m³sourcenominal, annealed and aged | 8,027kg/m³sourcetypical |
| Strength to weight | 147kN·m/kg4.45x higher | 33kN·m/kg |
| Stiffness to weight | 24.3MN·m/kg | 24.9MN·m/kg2% higher |
| Poisson's ratio | 0.294sourcetypical, 21 °C, annealed + aged | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 77.3GPa | 76.9GPa |
| Bulk modulus | 162GPa | 167GPa |
| Speed of sound | 4,932m/s | 4,992m/s |
| Thermal | ||
| Thermal conductivity | 11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a) | 14.6W/m·Ksource20–100 °C |
| Thermal expansion | 13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged | 16.5µm/m·Ksourcemean, 20–100 °C |
| 100 mm part over a 50 °C swing | 66µm growth25% less | 82.5µm growth |
| Specific heat | 435J/kg·Ksourcetypical, 21 °C | 450J/kg·Ksourceat 20 °C |
| Heats up and cools (diffusivity) | 3.19mm²/s | 4.04mm²/s27% faster |
| Thermal shock resistance | 3,680W/m4.48x more resistant | 821W/m |
| Melting point | 1,260–1,336°Csourcemelting range | 1,390–1,440°Csourcemelting range |
| Max service temperature | 704°Csourceupper use temperature stated by producer | 871–899°Csourceoxidation (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 | ATI 316 (UNS S31600), annealed 1.0 mm sheet, ATI technical data sheet (2012); 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 316?
Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 265 MPa for Stainless 316 (4.55x).
Which is lighter, Nickel Inconel 718 or Stainless 316?
Stainless 316 is lighter: 8,027 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.
Which is stiffer, Nickel Inconel 718 or Stainless 316?
Nickel Inconel 718 is stiffer: Young's modulus 200 GPa against 200 GPa for Stainless 316, 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 316?
For the same stiffness or strength: Nickel Inconel 718 is lighter for a strong rod or tie, strong beam, strong panel or plate; Stainless 316 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate.
| Part that must be | Nickel Inconel 718 | Stainless 316 |
|---|---|---|
| Stiff rod or tie (tension) | 2% heavier | lighter |
| Stiff beam (bending) | 2% heavier | lighter |
| Stiff panel or plate | 2% heavier | lighter |
| Strong rod or tie | lighter | 4.45x heavier |
| Strong beam | lighter | 2.68x heavier |
| Strong panel or plate | lighter | 2.08x 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 316?
Stainless 316 conducts heat better: 14.6 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 16.5 µm/m·K for Stainless 316.