Materials / Compare
Iron vs. Plastic PETG
Compare Iron vs. Plastic PETG 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 | 46.2MPasourcetypical |
| Ultimate tensile strength | 290MPasourcetypical, SRA/recrystallization anneal | 46.2MPasourcetypical, peak stress (= stress at yield) |
| Flexural strength | not sourced | 78.9MPasourcetypical |
| Elongation at break | 38%sourcetypical, gauge 4D0 | 7.6%sourcetypical |
| Young's modulus (stiffness) | 207GPasourcetypical, after SRA/recrystallization anneal | 1.94GPasourcetypical |
| Density | 7,860kg/m³sourcetypical | 1,270kg/m³sourcetypical6.19x lighter |
| Strength to weight | 23.7kN·m/kg | 36.4kN·m/kg1.54x higher |
| Stiffness to weight | 26.3MN·m/kg17.2x higher | 1.53MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | not sourced |
| Shear modulus | 80.7GPa | not sourced |
| Bulk modulus | 158GPa | not sourced |
| Speed of sound | 5,132m/s | 1,236m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 0.21W/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 51µm/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical |
| 100 mm part over a 50 °C swing | 68.5µm growth3.72x less | 255µm growth |
| Specific heat | 450J/kg·Ksourcetypical | 1,300J/kg·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), DSC at 60 °C (lowest temperature listed) |
| Heats up and cools (diffusivity) | 20.7mm²/s163x faster | 0.127mm²/s |
| Thermal shock resistance | 3,447W/m | not sourced |
| Melting point | 1,532°Csourcetypical | not sourced |
| Glass transition | not sourced | 77.4°Csourcetypical |
| Max service temperature | not sourced | 76.2°CsourceHDT 0.455 MPa (printed specimens) |
| 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. | Ultimaker PETG, 3D-printed specimens, XY (flat); Ultimaker S5 Pro, engineering intent profile, 0.15 mm layer height, AA 0.4 print core, 100% infill, Cura 4.9, printed one-at-a-time, conditioned >=24 h at room temperature. TDS v1.00, April 29, 2022. |
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.
Plastic PETG is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Is Iron stronger than Plastic PETG?
Iron is stronger: its yield strength is 186 MPa against 46.2 MPa for Plastic PETG (4.03x).
Which is lighter, Iron or Plastic PETG?
Plastic PETG is lighter: 1,270 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Iron or Plastic PETG?
Iron is stiffer: Young's modulus 207 GPa against 1.94 GPa for Plastic PETG, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Plastic PETG?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending); Plastic PETG is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | Plastic PETG |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 17.2x heavier |
| Stiff beam (bending) | lighter | 1.67x heavier |
| Stiff panel or plate | 30% heavier | lighter |
| Strong rod or tie | 1.54x heavier | lighter |
| Strong beam | 2.45x heavier | lighter |
| Strong panel or plate | 3.08x 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 PETG?
Iron conducts heat better: 73.2 W/m·K against 0.21 W/m·K for Plastic PETG.
Which expands less with temperature?
Iron expands less: 13.7 µm/m·K against 51 µm/m·K for Plastic PETG.