Materials / Compare
Plastic Polycarbonate vs. Stainless 304
Compare Plastic Polycarbonate vs. Stainless 304 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 | 241MPasourcetypical, annealed, 70 °F (21 °C) |
| Ultimate tensile strength | 65MPasourcetypical, stress at break | 586MPasourcetypical, annealed, 70 °F (21 °C) |
| Flexural strength | 97MPasourcetypical, flexural strength | not sourced |
| Elongation at break | 125%sourcetypical, strain at break | 55%sourcetypical, annealed, in 2 in. (50.8 mm) |
| Young's modulus (stiffness) | 2.4GPasourcetypical | 193GPasourcetypical, in tension |
| Density | 1,200kg/m³sourcetypical6.69x lighter | 8,030kg/m³sourcetypical |
| Strength to weight | 54.2kN·m/kg1.8x higher | 30kN·m/kg |
| Stiffness to weight | 2MN·m/kg | 24MN·m/kg12x higher |
| Poisson's ratio | 0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1) | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 0.87GPa | 74.2GPa85.4x stiffer in shear |
| Bulk modulus | 3.33GPa | 161GPa |
| Speed of sound | 1,414m/s | 4,903m/s |
| Thermal | ||
| Thermal conductivity | 0.2W/m·Ksourcetypical, through-plane, 23 C | 16.2W/m·Ksourceat 100 °C |
| Thermal expansion | 65µm/m·Ksourcetypical, 23-55 C, parallel and normal | 16.9µm/m·Ksourcemean, 0–100 °C |
| 100 mm part over a 50 °C swing | 325µm growth | 84.5µm growth3.85x less |
| Specific heat | 1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766 | 500J/kg·Ksourcemean, 0–100 °C |
| Heats up and cools (diffusivity) | 0.142mm²/s | 4.03mm²/s28.4x faster |
| Thermal shock resistance | 51.7W/m | 838W/m16.2x more resistant |
| Melting point | not sourced | 1,399–1,454°Csourcemelting range |
| Glass transition | 144°Csourcetypical, DSC 10 C/min | not sourced |
| Max service temperature | 125°CsourceUL 746B RTI, tensile strength, 1.5 mm | 899°Csourcecontinuous, oxidation (scaling) limit in air |
| Values for | Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values | Type 304, annealed flat-rolled (Cleveland-Cliffs 304/304L Product Data Bulletin, May 2021); Poisson's ratio from the Nickel Institute/SCI structural stainless design manual |
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 Stainless 304?
Stainless 304 is stronger: its yield strength is 241 MPa against 65 MPa for Plastic Polycarbonate (3.71x).
Which is lighter, Plastic Polycarbonate or Stainless 304?
Plastic Polycarbonate is lighter: 1,200 kg/m³ against 8,030 kg/m³ for Stainless 304.
Which is stiffer, Plastic Polycarbonate or Stainless 304?
Stainless 304 is stiffer: Young's modulus 193 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in Stainless 304 deflects less under the same load.
Which is lighter for the same job, Plastic Polycarbonate or Stainless 304?
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; Stainless 304 is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic Polycarbonate | Stainless 304 |
|---|---|---|
| Stiff rod or tie (tension) | 12x heavier | lighter |
| Stiff beam (bending) | 34% heavier | lighter |
| Stiff panel or plate | lighter | 1.55x heavier |
| Strong rod or tie | lighter | 1.8x heavier |
| Strong beam | lighter | 2.79x heavier |
| Strong panel or plate | lighter | 3.48x 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 Stainless 304?
Stainless 304 conducts heat better: 16.2 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.
Which expands less with temperature?
Stainless 304 expands less: 16.9 µm/m·K against 65 µm/m·K for Plastic Polycarbonate.