Materials / Compare
Plastic Polycarbonate vs. Steel
Compare Plastic Polycarbonate vs. Steel 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 | 65MPasourcetypical, tensile yield | 385MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey), as reported by AISC |
| Ultimate tensile strength | 65MPasourcetypical, stress at break | 505MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey) |
| Flexural strength | 97MPasourcetypical, flexural strength | not sourced |
| Elongation at break | 125%sourcetypical, strain at break | not sourced |
| Young's modulus (stiffness) | 2.4GPasourcetypical | 200GPasourcedesign value (AISC 360-16) |
| Density | 1,200kg/m³sourcetypical | 7,850kg/m³sourcenominal (constructional data) |
| Strength to weight | 54.2kN·m/kg10% higher | 49kN·m/kg |
| Stiffness to weight | 2MN·m/kg | 25.5MN·m/kg12.7x higher |
| Poisson's ratio | 0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1) | 0.3sourcedesign value (AISC 360-16 Commentary) |
| Shear modulus | 0.87GPa | 76.9GPa88.5x stiffer in shear |
| Bulk modulus | 3.33GPa | 167GPa |
| Speed of sound | 1,414m/s | 5,048m/s |
| Thermal | ||
| Thermal conductivity | 0.2W/m·Ksourcetypical, through-plane, 23 C | 48W/m·Ksourcenominal at 20 °C |
| Thermal expansion | 65µm/m·Ksourcetypical, 23-55 C, parallel and normal | 12µm/m·Ksourcenominal (constructional data, no temperature range stated) |
| 100 mm part over a 50 °C swing | 325µm growth | 60µm growth5.42x less |
| Specific heat | 1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766 | 460–480J/kg·Ksourcebase material: EN S275JR unalloyed structural steel (the EN counterpart of A36), typical, 50/100 °C |
| Heats up and cools (diffusivity) | 0.142mm²/s | 13mm²/s91.5x faster |
| Thermal shock resistance | 51.7W/m | 5,390W/m104x more resistant |
| Glass transition | 144°Csourcetypical, DSC 10 C/min | not sourced |
| Max service temperature | 125°CsourceUL 746B RTI, tensile strength, 1.5 mm | not sourced |
| Values for | Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values | Generic structural steel, cited as ASTM A992 (the current US structural grade): ASTM A992 W-shapes; Fy/Fu specified minimums from AISC publications (AISC 360-16 Commentary; Modern Steel Construction); elastic constants AISC 360; physical constants from the bauforumstahl structural-steel EPD, which names A992 among covered product standards. |
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 Polycarbonate stronger than Steel?
Steel is stronger: its yield strength is 385 MPa against 65 MPa for Plastic Polycarbonate (5.92x).
Which is lighter, Plastic Polycarbonate or Steel?
Plastic Polycarbonate is lighter: 1,200 kg/m³ against 7,850 kg/m³ for Steel.
Which is stiffer, Plastic Polycarbonate or Steel?
Steel is stiffer: Young's modulus 200 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in Steel deflects less under the same load.
Which is lighter for the same job, Plastic Polycarbonate or Steel?
For the same stiffness or strength: Plastic Polycarbonate is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Steel is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic Polycarbonate | Steel |
|---|---|---|
| Stiff rod or tie (tension) | 12.7x heavier | lighter |
| Stiff beam (bending) | 40% heavier | lighter |
| Stiff panel or plate | lighter | 50% heavier |
| Strong rod or tie | lighter | 10% heavier |
| Strong beam | lighter | 2x heavier |
| Strong panel or plate | lighter | 2.69x 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 Polycarbonate or Steel?
Steel conducts heat better: 48 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.
Which expands less with temperature?
Steel expands less: 12 µm/m·K against 65 µm/m·K for Plastic Polycarbonate.