Materials / Compare
Plastic HDPE vs. Stainless 304
Compare Plastic HDPE vs. Stainless 304 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 | 241MPasourcetypical, annealed, 70 °F (21 °C) |
| Ultimate tensile strength | not sourced | 586MPasourcetypical, annealed, 70 °F (21 °C) |
| Elongation at break | not sourced | 55%sourcetypical, annealed, in 2 in. (50.8 mm) |
| Young's modulus (stiffness) | 0.9GPasourcetypical, tensile modulus 23 °C ISO 527 | 193GPasourcetypical, in tension |
| Density | 950kg/m³sourcetypical, ISO 1183 | 8,030kg/m³sourcetypical |
| Strength to weight | 25.3kN·m/kg | 30kN·m/kg19% higher |
| Stiffness to weight | 0.947MN·m/kg | 24MN·m/kg25.4x higher |
| Poisson's ratio | 0.4–0.45sourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 0.316GPa | 74.2GPa235x stiffer in shear |
| Bulk modulus | 2GPa | 161GPa |
| Speed of sound | 973m/s | 4,903m/s |
| Thermal | ||
| Thermal conductivity | 0.4–0.49W/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 16.2W/m·Ksourceat 100 °C |
| Thermal expansion | 120µm/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 16.9µm/m·Ksourcemean, 0–100 °C |
| 100 mm part over a 50 °C swing | 600µm growth | 84.5µm growth7.1x less |
| Specific heat | 2,250J/kg·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 500J/kg·Ksourcemean, 0–100 °C |
| Heats up and cools (diffusivity) | 0.208mm²/s | 4.03mm²/s19.4x faster |
| Thermal shock resistance | 56.9W/m | 838W/m14.7x more resistant |
| Melting point | not sourced | 1,399–1,454°Csourcemelting range |
| Max service temperature | not sourced | 899°Csourcecontinuous, oxidation (scaling) limit in air |
| Values for | LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO 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 Plastic HDPE stronger than Stainless 304?
Stainless 304 is stronger: its yield strength is 241 MPa against 24 MPa for Plastic HDPE (10x).
Which is lighter, Plastic HDPE or Stainless 304?
Plastic HDPE is lighter: 950 kg/m³ against 8,030 kg/m³ for Stainless 304.
Which is stiffer, Plastic HDPE or Stainless 304?
Stainless 304 is stiffer: Young's modulus 193 GPa against 0.9 GPa for Plastic HDPE, so the same part in Stainless 304 deflects less under the same load.
Which is lighter for the same job, Plastic HDPE or Stainless 304?
For the same stiffness or strength: Plastic HDPE is lighter for a stiff panel or plate, strong beam, strong panel or plate; Stainless 304 is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie.
| Part that must be | Plastic HDPE | Stainless 304 |
|---|---|---|
| Stiff rod or tie (tension) | 25.4x heavier | lighter |
| Stiff beam (bending) | 1.73x heavier | lighter |
| Stiff panel or plate | lighter | 41% heavier |
| Strong rod or tie | 19% heavier | lighter |
| Strong beam | lighter | 1.82x heavier |
| Strong panel or plate | lighter | 2.67x 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 Stainless 304?
Stainless 304 conducts heat better: 16.2 W/m·K against 0.445 W/m·K for Plastic HDPE.
Which expands less with temperature?
Stainless 304 expands less: 16.9 µm/m·K against 120 µm/m·K for Plastic HDPE.