Materials / Compare
Plastic HDPE vs. Nickel Inconel 718
Compare Plastic HDPE 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 | 24MPasourcetypical, tensile stress at yield 23 °C, 50 mm/min ISO 527 | 1,207MPasourcetypical, 1.0 in. hot-rolled bar, 0.2% offset |
| Ultimate tensile strength | not sourced | 1,389MPasourcetypical, 1.0 in. bar |
| Elongation at break | not sourced | 20%sourcetypical, 1.0 in. bar |
| Young's modulus (stiffness) | 0.9GPasourcetypical, tensile modulus 23 °C ISO 527 | 200GPasourcetypical, 21 °C, annealed + aged |
| Density | 950kg/m³sourcetypical, ISO 1183 | 8,221kg/m³sourcenominal, annealed and aged |
| Strength to weight | 25.3kN·m/kg | 147kN·m/kg5.81x higher |
| Stiffness to weight | 0.947MN·m/kg | 24.3MN·m/kg25.7x higher |
| Poisson's ratio | 0.4–0.45sourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.294sourcetypical, 21 °C, annealed + aged |
| Shear modulus | 0.316GPa | 77.3GPa245x stiffer in shear |
| Bulk modulus | 2GPa | 162GPa |
| Speed of sound | 973m/s | 4,932m/s |
| Thermal | ||
| Thermal conductivity | 0.4–0.49W/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a) |
| Thermal expansion | 120µm/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged |
| 100 mm part over a 50 °C swing | 600µm growth | 66µm growth9.09x less |
| Specific heat | 2,250J/kg·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 435J/kg·Ksourcetypical, 21 °C |
| Heats up and cools (diffusivity) | 0.208mm²/s | 3.19mm²/s15.3x faster |
| Thermal shock resistance | 56.9W/m | 3,680W/m64.7x more resistant |
| Melting point | not sourced | 1,260–1,336°Csourcemelting range |
| Max service temperature | not sourced | 704°Csourceupper use temperature stated by producer |
| Values for | LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values | 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 Plastic HDPE stronger than Nickel Inconel 718?
Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 24 MPa for Plastic HDPE (50.3x).
Which is lighter, Plastic HDPE or Nickel Inconel 718?
Plastic HDPE is lighter: 950 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.
Which is stiffer, Plastic HDPE or Nickel Inconel 718?
Nickel Inconel 718 is stiffer: Young's modulus 200 GPa against 0.9 GPa for Plastic HDPE, so the same part in Nickel Inconel 718 deflects less under the same load.
Which is lighter for the same job, Plastic HDPE or Nickel Inconel 718?
For the same stiffness or strength: Plastic HDPE is lighter for a stiff panel or plate, strong panel or plate; Nickel Inconel 718 is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie, strong beam.
| Part that must be | Plastic HDPE | Nickel Inconel 718 |
|---|---|---|
| Stiff rod or tie (tension) | 25.7x heavier | lighter |
| Stiff beam (bending) | 1.72x heavier | lighter |
| Stiff panel or plate | lighter | 43% heavier |
| Strong rod or tie | 5.81x heavier | lighter |
| Strong beam | 1.57x heavier | lighter |
| Strong panel or plate | lighter | 22% 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, Plastic HDPE or Nickel Inconel 718?
Nickel Inconel 718 conducts heat better: 11.4 W/m·K against 0.445 W/m·K for Plastic HDPE.
Which expands less with temperature?
Nickel Inconel 718 expands less: 13.2 µm/m·K against 120 µm/m·K for Plastic HDPE.