Materials / Compare
Iron vs. Plastic PMMA
Compare Iron vs. Plastic PMMA 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 | not given (tensile used) |
| Ultimate tensile strength | 290MPasourcetypical, SRA/recrystallization anneal | 80MPasourcetypical, 23 °C |
| Compressive strength | not sourced | 110MPasourcecompressive yield stress, typical |
| Flexural strength | not sourced | 115MPasourcetypical |
| Elongation at break | 38%sourcetypical, gauge 4D0 | 5.5%sourcetypical |
| Young's modulus (stiffness) | 207GPasourcetypical, after SRA/recrystallization anneal | 3.3GPasourcetypical, short-term |
| Density | 7,860kg/m³sourcetypical | 1,190kg/m³sourcetypical6.61x lighter |
| Strength to weight | 23.7kN·m/kg | 67.2kN·m/kg2.84x higher |
| Stiffness to weight | 26.3MN·m/kg9.5x higher | 2.77MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | 0.37sourcetypical |
| Shear modulus | 80.7GPa67x stiffer in shear | 1.2GPa |
| Bulk modulus | 158GPa | 4.23GPa |
| Speed of sound | 5,132m/s | 1,665m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 0.19W/m·Ksourcetypical |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 70µm/m·Ksource0-50 °C |
| 100 mm part over a 50 °C swing | 68.5µm growth5.11x less | 350µm growth |
| Specific heat | 450J/kg·Ksourcetypical | 1,470J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 20.7mm²/s191x faster | 0.109mm²/s |
| Thermal shock resistance | 3,447W/m83.2x more resistant | 41.5W/m |
| Melting point | 1,532°Csourcetypical | not sourced |
| Max service temperature | not sourced | 80°Csourcemax. permanent service temperature |
| 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. | Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1) |
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 PMMA?
Iron is stronger: its yield strength is 186 MPa against tensile strength 80 MPa for Plastic PMMA (2.33x).
Which is lighter, Iron or Plastic PMMA?
Plastic PMMA is lighter: 1,190 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Iron or Plastic PMMA?
Iron is stiffer: Young's modulus 207 GPa against 3.3 GPa for Plastic PMMA, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Plastic PMMA?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending); Plastic PMMA is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | Plastic PMMA |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 9.5x heavier |
| Stiff beam (bending) | lighter | 20% heavier |
| Stiff panel or plate | 1.66x heavier | lighter |
| Strong rod or tie | 2.84x heavier | lighter |
| Strong beam | 3.76x heavier | lighter |
| Strong panel or plate | 4.33x 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 PMMA?
Iron conducts heat better: 73.2 W/m·K against 0.19 W/m·K for Plastic PMMA.
Which expands less with temperature?
Iron expands less: 13.7 µm/m·K against 70 µm/m·K for Plastic PMMA.