Materials / Compare
Plastic TPU vs. Steel AISI 4340
Compare Plastic TPU 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 | not given (tensile used) | 1,035MPasourcetypical, transverse |
| Ultimate tensile strength | 23.7MPasourcetypical, stress at break | 1,140MPasourcetypical, transverse |
| Flexural strength | 4.1MPasourcetypical | not sourced |
| Elongation at break | not sourced | 18%sourcetypical, transverse |
| Young's modulus (stiffness) | 0.067GPasourcetypical | 200GPasourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered) |
| Density | 1,220kg/m³sourcetypical6.43x lighter | 7,840kg/m³sourcetypical |
| Strength to weight | 19.4kN·m/kg | 132kN·m/kg6.8x higher |
| Stiffness to weight | 0.0549MN·m/kg | 25.5MN·m/kg464x 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 | 234m/s | 5,049m/s |
| Thermal | ||
| Thermal conductivity | not sourced | 37.5W/m·Ksourcetypical |
| Thermal expansion | not sourced | 11.3µm/m·Ksourcemean, -18 to 93 °C |
| 100 mm part over a 50 °C swing | not sourced | 56.5µm growth |
| 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 | 217°Csourcetypical | not sourced |
| Max service temperature | 50.3°CsourceHDT 0.455 MPa (printed specimens) | not sourced |
| Values for | Ultimaker TPU 95A, 3D-printed specimens, XY (flat); Ultimaker S5 Pro, engineering intent profile, 0.15 mm layer height, AA 0.4 print core, 100% infill, Cura 4.9, printed one-at-a-time, conditioned >=24 h at room temperature. TDS (file v5.00), April 29, 2022. | 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.
Plastic TPU is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Is Plastic TPU stronger than Steel AISI 4340?
Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against tensile strength 23.7 MPa for Plastic TPU (43.7x).
Which is lighter, Plastic TPU or Steel AISI 4340?
Plastic TPU is lighter: 1,220 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.
Which is stiffer, Plastic TPU or Steel AISI 4340?
Steel AISI 4340 is stiffer: Young's modulus 200 GPa against 0.067 GPa for Plastic TPU, so the same part in Steel AISI 4340 deflects less under the same load.
Which is lighter for the same job, Plastic TPU or Steel AISI 4340?
For the same stiffness or strength: Steel AISI 4340 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Plastic TPU | Steel AISI 4340 |
|---|---|---|
| Stiff rod or tie (tension) | 464x heavier | lighter |
| Stiff beam (bending) | 8.5x heavier | lighter |
| Stiff panel or plate | 2.24x heavier | lighter |
| Strong rod or tie | 6.8x heavier | lighter |
| Strong beam | 1.93x heavier | lighter |
| Strong panel or plate | 3% 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).