Materials / Compare
Plastic HDPE vs. Iron
Compare Plastic HDPE vs. Iron 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 | 186MPasourcetypical (0.2% YS), hot rolled + SRA/recrystallization anneal |
| Ultimate tensile strength | not sourced | 290MPasourcetypical, SRA/recrystallization anneal |
| Elongation at break | not sourced | 38%sourcetypical, gauge 4D0 |
| Young's modulus (stiffness) | 0.9GPasourcetypical, tensile modulus 23 °C ISO 527 | 207GPasourcetypical, after SRA/recrystallization anneal |
| Density | 950kg/m³sourcetypical, ISO 1183 | 7,860kg/m³sourcetypical |
| Strength to weight | 25.3kN·m/kg7% higher | 23.7kN·m/kg |
| Stiffness to weight | 0.947MN·m/kg | 26.3MN·m/kg27.8x higher |
| Poisson's ratio | 0.4–0.45sourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 0.282sourceNIST critically evaluated best value (polycrystalline iron) |
| Shear modulus | 0.316GPa | 80.7GPa256x stiffer in shear |
| Bulk modulus | 2GPa | 158GPa |
| Speed of sound | 973m/s | 5,132m/s |
| Thermal | ||
| Thermal conductivity | 0.4–0.49W/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 73.2W/m·Ksourcetypical at 20 °C |
| Thermal expansion | 120µm/m·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 13.7µm/m·Ksourcemean, 20-399 °C |
| 100 mm part over a 50 °C swing | 600µm growth | 68.5µm growth8.76x less |
| Specific heat | 2,250J/kg·Ksourcebase material: high-density polyethylene family (INEOS Olefins & Polymers USA, Typical Engineering Properties of HDPE) | 450J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.208mm²/s | 20.7mm²/s99.4x faster |
| Thermal shock resistance | 56.9W/m | 3,447W/m60.6x more resistant |
| Melting point | not sourced | 1,532°Csourcetypical |
| Values for | LyondellBasell Hostalen 23050 B high density polyethylene, typical ISO values | 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. |
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 Iron?
Iron is stronger: its yield strength is 186 MPa against 24 MPa for Plastic HDPE (7.75x).
Which is lighter, Plastic HDPE or Iron?
Plastic HDPE is lighter: 950 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Plastic HDPE or Iron?
Iron is stiffer: Young's modulus 207 GPa against 0.9 GPa for Plastic HDPE, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Plastic HDPE or Iron?
For the same stiffness or strength: Plastic HDPE is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Iron is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic HDPE | Iron |
|---|---|---|
| Stiff rod or tie (tension) | 27.8x heavier | lighter |
| Stiff beam (bending) | 1.83x heavier | lighter |
| Stiff panel or plate | lighter | 35% heavier |
| Strong rod or tie | lighter | 7% heavier |
| Strong beam | lighter | 2.11x heavier |
| Strong panel or plate | lighter | 2.97x 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 Iron?
Iron conducts heat better: 73.2 W/m·K against 0.445 W/m·K for Plastic HDPE.
Which expands less with temperature?
Iron expands less: 13.7 µm/m·K against 120 µm/m·K for Plastic HDPE.