Materials / Compare
Plastic UHMWPE vs. Steel AISI 4340
Compare Plastic UHMWPE 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 | 20MPasourcetypical, tensile stress at yield ISO 527, 50 mm/min | 1,035MPasourcetypical, transverse |
| Ultimate tensile strength | 43MPasourcetypical, tensile stress at break ISO 527, 50 mm/min | 1,140MPasourcetypical, transverse |
| Elongation at break | 465%sourcetypical, nominal elongation at break ISO 527 | 18%sourcetypical, transverse |
| Young's modulus (stiffness) | 0.66GPasourcetypical, tensile modulus ISO 527, 1 mm/min | 200GPasourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered) |
| Density | 930kg/m³sourcetypical8.43x lighter | 7,840kg/m³sourcetypical |
| Strength to weight | 21.5kN·m/kg | 132kN·m/kg6.14x higher |
| Stiffness to weight | 0.71MN·m/kg | 25.5MN·m/kg35.9x higher |
| Poisson's ratio | not sourced | 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 | 842m/s | 5,049m/s |
| Thermal | ||
| Thermal conductivity | 0.4W/m·Ksourcetypical, unfilled (narrative value, generic Celanese UHMWPE) | 37.5W/m·Ksourcetypical |
| Thermal expansion | 200µm/m·Ksourcetypical, 20 to 100 °C (generic Celanese UHMWPE) | 11.3µm/m·Ksourcemean, -18 to 93 °C |
| 100 mm part over a 50 °C swing | 1,000µm growth | 56.5µm growth17.7x less |
| Specific heat | not sourced | 448J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | not sourced | 10.7mm²/s |
| Thermal shock resistance | not sourced | 11,678W/m |
| Melting point | 130–138°CsourceDSC 10 K/min | not sourced |
| Max service temperature | 80°Csourcerecommended max constant operating temperature | not sourced |
| Values for | Celanese GUR 4120 (avg. molecular weight 4.7x10^6 g/mol), typical values on compression-molded specimens; CTE and thermal conductivity from Celanese's generic UHMWPE guide (grade not named) | 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 UHMWPE stronger than Steel AISI 4340?
Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against 20 MPa for Plastic UHMWPE (51.8x).
Which is lighter, Plastic UHMWPE or Steel AISI 4340?
Plastic UHMWPE is lighter: 930 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.
Which is stiffer, Plastic UHMWPE or Steel AISI 4340?
Steel AISI 4340 is stiffer: Young's modulus 200 GPa against 0.66 GPa for Plastic UHMWPE, so the same part in Steel AISI 4340 deflects less under the same load.
Which is lighter for the same job, Plastic UHMWPE or Steel AISI 4340?
For the same stiffness or strength: Plastic UHMWPE is lighter for a stiff panel or plate, strong panel or plate; Steel AISI 4340 is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie, strong beam.
| Part that must be | Plastic UHMWPE | Steel AISI 4340 |
|---|---|---|
| Stiff rod or tie (tension) | 35.9x heavier | lighter |
| Stiff beam (bending) | 2.06x heavier | lighter |
| Stiff panel or plate | lighter | 26% heavier |
| Strong rod or tie | 6.14x heavier | lighter |
| Strong beam | 1.65x heavier | lighter |
| Strong panel or plate | lighter | 17% 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 UHMWPE or Steel AISI 4340?
Steel AISI 4340 conducts heat better: 37.5 W/m·K against 0.4 W/m·K for Plastic UHMWPE.
Which expands less with temperature?
Steel AISI 4340 expands less: 11.3 µm/m·K against 200 µm/m·K for Plastic UHMWPE.