Materials / Compare
Plastic PTFE vs. Steel AISI 4340
Compare Plastic PTFE vs. Steel AISI 4340 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 | 9MPasourcetypical yield strength at 23 °C (Teflon PTFE, Table 8) | 1,035MPasourcetypical, transverse |
| Ultimate tensile strength | 39.3MPasourcetypical, skived tape 0.13 mm | 1,140MPasourcetypical, transverse |
| Elongation at break | 350%sourcetypical, skived tape 0.13 mm | 18%sourcetypical, transverse |
| Young's modulus (stiffness) | not sourced | 200GPasourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered) |
| Density | 2,160kg/m³sourcetypical (standard specific gravity, ASTM D4894) | 7,840kg/m³sourcetypical |
| Strength to weight | 4.17kN·m/kg | 132kN·m/kg31.7x higher |
| Stiffness to weight | not sourced | 25.5MN·m/kg |
| Poisson's ratio | 0.46sourcetypical, 23 °C (Teflon PTFE resins, Chemours handbook) | 0.32sourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered) |
| Shear modulus | not sourced | 75.7GPa |
| Bulk modulus | not sourced | 185GPa |
| Speed of sound | not sourced | 5,049m/s |
| Thermal | ||
| Thermal conductivity | 0.25W/m·Ksourcetypical, granular resin, 4.6 mm specimen | 37.5W/m·Ksourcetypical |
| Thermal expansion | 100µm/m·Ksourcetypical, granular resin, 23-60 °C (ASTM E228) | 11.3µm/m·Ksourcemean, -18 to 93 °C |
| 100 mm part over a 50 °C swing | 500µm growth | 56.5µm growth8.85x less |
| Specific heat | 1,400J/kg·Ksourcetypical, granular resin, 20 °C (ASTM D4591) | 448J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.0827mm²/s | 10.7mm²/s129x faster |
| Thermal shock resistance | not sourced | 11,678W/m |
| Melting point | 327°Csourcesecond melting peak (sintered polymer), +/-10 | not sourced |
| Max service temperature | 260°Csourceservice temperature (Chemours general Teflon PTFE statement) | not sourced |
| Values for | Chemours Teflon PTFE 7C X granular molding resin, typical values (tensile/elongation measured on 0.13 mm skived tape) | Carpenter (Latrobe) Lescalloy 4340 VAC-ARC datasheet; mechanical row for 1100 °F temper; physical properties grade-level |
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 PTFE stronger than Steel AISI 4340?
Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against 9 MPa for Plastic PTFE (115x).
Which is lighter, Plastic PTFE or Steel AISI 4340?
Plastic PTFE is lighter: 2,160 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.
Which is lighter for the same job, Plastic PTFE or Steel AISI 4340?
For the same stiffness or strength: Steel AISI 4340 is lighter for a strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Plastic PTFE | Steel AISI 4340 |
|---|---|---|
| Strong rod or tie | 31.7x heavier | lighter |
| Strong beam | 6.52x heavier | lighter |
| Strong panel or plate | 2.95x heavier | lighter |
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 PTFE or Steel AISI 4340?
Steel AISI 4340 conducts heat better: 37.5 W/m·K against 0.25 W/m·K for Plastic PTFE.
Which expands less with temperature?
Steel AISI 4340 expands less: 11.3 µm/m·K against 100 µm/m·K for Plastic PTFE.