Materials / Compare
Plastic PMMA vs. Steel AISI 1045
Compare Plastic PMMA vs. Steel AISI 1045 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) | 531MPasourceproducer-stated, cold drawn |
| Ultimate tensile strength | 80MPasourcetypical, 23 °C | 627MPasourceproducer-stated, cold drawn |
| Compressive strength | 110MPasourcecompressive yield stress, typical | not sourced |
| Flexural strength | 115MPasourcetypical | not sourced |
| Elongation at break | 5.5%sourcetypical | 12%sourcein 2 in (50.8 mm) |
| Young's modulus (stiffness) | 3.3GPasourcetypical, short-term | 210GPasourcetypical |
| Density | 1,190kg/m³sourcetypical6.55x lighter | 7,800kg/m³sourcetypical |
| Strength to weight | 67.2kN·m/kg | 68.1kN·m/kg1% higher |
| Stiffness to weight | 2.77MN·m/kg | 26.9MN·m/kg9.71x higher |
| Poisson's ratio | 0.37sourcetypical | 0.3sourcetypical |
| Shear modulus | 1.2GPa | 80.8GPa67.1x stiffer in shear |
| Bulk modulus | 4.23GPa | 175GPa |
| Speed of sound | 1,665m/s | 5,189m/s |
| Thermal | ||
| Thermal conductivity | 0.19W/m·Ksourcetypical | 40–45W/m·Ksourcetypical range, ambient |
| Thermal expansion | 70µm/m·Ksource0-50 °C | 12µm/m·Ksourcetypical, mean 20-300 °C |
| 100 mm part over a 50 °C swing | 350µm growth | 60µm growth5.83x less |
| Specific heat | 1,470J/kg·Ksourcetypical | 460–480J/kg·Ksourcetypical range, 50/100 °C |
| Heats up and cools (diffusivity) | 0.109mm²/s | 11.6mm²/s107x faster |
| Thermal shock resistance | 41.5W/m | 6,269W/m151x 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 1045 cold drawn bar (Niagara LaSalle) for mechanical; Ovako C45 (lists 'SAE 1045' as a similar designation) for physical constants |
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 1045?
Steel AISI 1045 is stronger: its yield strength is 531 MPa against tensile strength 80 MPa for Plastic PMMA (6.64x).
Which is lighter, Plastic PMMA or Steel AISI 1045?
Plastic PMMA is lighter: 1,190 kg/m³ against 7,800 kg/m³ for Steel AISI 1045.
Which is stiffer, Plastic PMMA or Steel AISI 1045?
Steel AISI 1045 is stiffer: Young's modulus 210 GPa against 3.3 GPa for Plastic PMMA, so the same part in Steel AISI 1045 deflects less under the same load.
Which is lighter for the same job, Plastic PMMA or Steel AISI 1045?
For the same stiffness or strength: Plastic PMMA is lighter for a stiff panel or plate, strong beam, strong panel or plate; Steel AISI 1045 is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie.
| Part that must be | Plastic PMMA | Steel AISI 1045 |
|---|---|---|
| Stiff rod or tie (tension) | 9.71x heavier | lighter |
| Stiff beam (bending) | 22% heavier | lighter |
| Stiff panel or plate | lighter | 1.64x heavier |
| Strong rod or tie | 1% heavier | lighter |
| Strong beam | lighter | 1.86x heavier |
| Strong panel or plate | lighter | 2.54x 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 1045?
Steel AISI 1045 conducts heat better: 42.5 W/m·K against 0.19 W/m·K for Plastic PMMA.
Which expands less with temperature?
Steel AISI 1045 expands less: 12 µm/m·K against 70 µm/m·K for Plastic PMMA.