Materials / Compare
Plastic Polycarbonate vs. Stainless 303
Compare Plastic Polycarbonate vs. Stainless 303 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 | 275MPasourceOutokumpu typical (product P = hot rolled plate, transverse) |
| Ultimate tensile strength | 65MPasourcetypical, stress at break | 585MPasourceOutokumpu typical |
| Flexural strength | 97MPasourcetypical, flexural strength | not sourced |
| Elongation at break | 125%sourcetypical, strain at break | 35%sourceOutokumpu typical, A5 |
| Young's modulus (stiffness) | 2.4GPasourcetypical | 200GPasourceat RT (Table 12) |
| Density | 1,200kg/m³sourcetypical | 7,900kg/m³sourceat RT |
| Strength to weight | 54.2kN·m/kg1.56x higher | 34.8kN·m/kg |
| Stiffness to weight | 2MN·m/kg | 25.3MN·m/kg12.7x 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 | 76.9GPa88.5x stiffer in shear |
| Bulk modulus | 3.33GPa | 167GPa |
| Speed of sound | 1,414m/s | 5,032m/s |
| Thermal | ||
| Thermal conductivity | 0.2W/m·Ksourcetypical, through-plane, 23 C | 15W/m·Ksourceat RT |
| Thermal expansion | 65µm/m·Ksourcetypical, 23-55 C, parallel and normal | 16µm/m·Ksourcemean, 20–100 °C |
| 100 mm part over a 50 °C swing | 325µm growth | 80µm growth4.06x less |
| Specific heat | 1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766 | 500J/kg·Ksourceat RT |
| Heats up and cools (diffusivity) | 0.142mm²/s | 3.8mm²/s26.7x faster |
| Thermal shock resistance | 51.7W/m | 902W/m17.5x more resistant |
| Glass transition | 144°Csourcetypical, DSC 10 C/min | not sourced |
| Max service temperature | 125°CsourceUL 746B RTI, tensile strength, 1.5 mm | 871°Csourcecontinuous, scaling limit |
| Values for | Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values | 1.4305 / UNS S30300, Outokumpu typical values (hot rolled, solution annealed) from 'Steel Grades, Properties and Global Standards'; max service from Carpenter CarTech 303 datasheet |
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 303?
Stainless 303 is stronger: its yield strength is 275 MPa against 65 MPa for Plastic Polycarbonate (4.23x).
Which is lighter, Plastic Polycarbonate or Stainless 303?
Plastic Polycarbonate is lighter: 1,200 kg/m³ against 7,900 kg/m³ for Stainless 303.
Which is stiffer, Plastic Polycarbonate or Stainless 303?
Stainless 303 is stiffer: Young's modulus 200 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in Stainless 303 deflects less under the same load.
Which is lighter for the same job, Plastic Polycarbonate or Stainless 303?
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 303 is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic Polycarbonate | Stainless 303 |
|---|---|---|
| Stiff rod or tie (tension) | 12.7x heavier | lighter |
| Stiff beam (bending) | 39% heavier | lighter |
| Stiff panel or plate | lighter | 1.51x heavier |
| Strong rod or tie | lighter | 1.56x heavier |
| Strong beam | lighter | 2.52x heavier |
| Strong panel or plate | lighter | 3.2x 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 303?
Stainless 303 conducts heat better: 15 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.
Which expands less with temperature?
Stainless 303 expands less: 16 µm/m·K against 65 µm/m·K for Plastic Polycarbonate.