Materials / Compare
Iron vs. Plastic Polypropylene
Compare Iron vs. Plastic Polypropylene 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 | 33MPasourcetypical, tensile stress at yield 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 | 1.45GPasourcetypical, tensile modulus ISO 527 |
| Density | 7,860kg/m³sourcetypical | 900kg/m³sourcetypical, 23 °C ISO 1183-1 |
| Strength to weight | 23.7kN·m/kg | 36.7kN·m/kg1.55x higher |
| Stiffness to weight | 26.3MN·m/kg16.3x higher | 1.61MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | 0.42sourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| Shear modulus | 80.7GPa158x stiffer in shear | 0.511GPa |
| Bulk modulus | 158GPa | 3.02GPa |
| Speed of sound | 5,132m/s | 1,269m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 0.17–0.22W/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 80–100µm/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) |
| 100 mm part over a 50 °C swing | 68.5µm growth6.57x less | 450µm growth |
| Specific heat | 450J/kg·Ksourcetypical | not sourced |
| Heats up and cools (diffusivity) | 20.7mm²/s | not sourced |
| Thermal shock resistance | 3,447W/m121x more resistant | 28.6W/m |
| Melting point | 1,532°Csourcetypical | not sourced |
| Max service temperature | not sourced | 90°CsourceHDT 0.45 MPa (ISO 75B), unannealed |
| 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 Moplen HP501H polypropylene homopolymer (general purpose), 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 Polypropylene?
Iron is stronger: its yield strength is 186 MPa against 33 MPa for Plastic Polypropylene (5.64x).
Which is lighter, Iron or Plastic Polypropylene?
Plastic Polypropylene is lighter: 900 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Iron or Plastic Polypropylene?
Iron is stiffer: Young's modulus 207 GPa against 1.45 GPa for Plastic Polypropylene, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Plastic Polypropylene?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending); Plastic Polypropylene is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | Plastic Polypropylene |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 16.3x heavier |
| Stiff beam (bending) | lighter | 37% heavier |
| Stiff panel or plate | 1.67x heavier | lighter |
| Strong rod or tie | 1.55x heavier | lighter |
| Strong beam | 2.76x heavier | lighter |
| Strong panel or plate | 3.68x 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 Polypropylene?
Iron conducts heat better: 73.2 W/m·K against 0.195 W/m·K for Plastic Polypropylene.
Which expands less with temperature?
Iron expands less: 13.7 µm/m·K against 90 µm/m·K for Plastic Polypropylene.