Materials / Compare
Plastic PMMA vs. Steel AISI 1018
Compare Plastic PMMA vs. Steel AISI 1018 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 | not given (tensile used) | 372MPasourceproducer-stated, cold drawn |
| Ultimate tensile strength | 80MPasourcetypical, 23 °C | 441MPasourceproducer-stated, cold drawn |
| Compressive strength | 110MPasourcecompressive yield stress, typical | not sourced |
| Flexural strength | 115MPasourcetypical | not sourced |
| Elongation at break | 5.5%sourcetypical | 15%sourcein 2 in (50.8 mm) |
| Young's modulus (stiffness) | 3.3GPasourcetypical, short-term | 200GPasourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Density | 1,190kg/m³sourcetypical | 7,861kg/m³sourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Strength to weight | 67.2kN·m/kg42% higher | 47.3kN·m/kg |
| Stiffness to weight | 2.77MN·m/kg | 25.4MN·m/kg9.17x higher |
| Poisson's ratio | 0.37sourcetypical | 0.32sourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Shear modulus | 1.2GPa | 75.7GPa62.9x stiffer in shear |
| Bulk modulus | 4.23GPa | 185GPa |
| Speed of sound | 1,665m/s | 5,043m/s |
| Thermal | ||
| Thermal conductivity | 0.19W/m·Ksourcetypical | 51.9W/m·Ksourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Thermal expansion | 70µm/m·Ksource0-50 °C | 12µm/m·Ksourcebase material: unalloyed carbon steel, Ovako family table (S275JR, 'none alloyed structural steels', C <= 0.21%); mean 20-300 °C |
| 100 mm part over a 50 °C swing | 350µm growth | 60µm growth5.83x less |
| Specific heat | 1,470J/kg·Ksourcetypical | 486J/kg·Ksourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Heats up and cools (diffusivity) | 0.109mm²/s | 13.6mm²/s125x faster |
| Thermal shock resistance | 41.5W/m | 5,473W/m132x more resistant |
| Max service temperature | 80°Csourcemax. permanent service temperature | not sourced |
| Values for | Röhm PLEXIGLAS GS 0F00 cast acrylic sheet, typical values at 23 °C / 50 % RH (Röhm Technical Information Ref. No. 211-1) | AISI 1018 cold drawn bar (Niagara LaSalle, cold-finished bar producer) |
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 PMMA stronger than Steel AISI 1018?
Steel AISI 1018 is stronger: its yield strength is 372 MPa against tensile strength 80 MPa for Plastic PMMA (4.65x).
Which is lighter, Plastic PMMA or Steel AISI 1018?
Plastic PMMA is lighter: 1,190 kg/m³ against 7,861 kg/m³ for Steel AISI 1018.
Which is stiffer, Plastic PMMA or Steel AISI 1018?
Steel AISI 1018 is stiffer: Young's modulus 200 GPa against 3.3 GPa for Plastic PMMA, so the same part in Steel AISI 1018 deflects less under the same load.
Which is lighter for the same job, Plastic PMMA or Steel AISI 1018?
For the same stiffness or strength: Plastic PMMA is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Steel AISI 1018 is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic PMMA | Steel AISI 1018 |
|---|---|---|
| Stiff rod or tie (tension) | 9.17x heavier | lighter |
| Stiff beam (bending) | 18% heavier | lighter |
| Stiff panel or plate | lighter | 1.68x heavier |
| Strong rod or tie | lighter | 42% heavier |
| Strong beam | lighter | 2.37x heavier |
| Strong panel or plate | lighter | 3.06x 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 PMMA or Steel AISI 1018?
Steel AISI 1018 conducts heat better: 51.9 W/m·K against 0.19 W/m·K for Plastic PMMA.
Which expands less with temperature?
Steel AISI 1018 expands less: 12 µm/m·K against 70 µm/m·K for Plastic PMMA.