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