Materials / Compare
Plastic PEEK vs. DMLS 316L Stainless Steel
Compare Plastic PEEK vs. DMLS 316L Stainless Steel 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 | 98MPasourcetypical, tensile yield | 530MPasourcetypical, as manufactured, horizontal |
| Ultimate tensile strength | not sourced | 640MPasourcetypical, as manufactured, horizontal |
| Compressive strength | 125MPasourcetypical, 23 C | not sourced |
| Flexural strength | 165MPasourcetypical, flexural stress at yield, 23 C | not sourced |
| Elongation at break | 25%sourcetypical, at break | 40%sourcetypical at break, as manufactured, horizontal |
| Young's modulus (stiffness) | 4GPasourcetypical (nominal) | 185GPasourcetypical, as built, horizontal (XY); EOSINT M280-400W / M290-400W, 316L_Surface 1.0, 20 µm (2014 sheet) |
| Density | 1,300kg/m³sourcetypical (crystalline) | 7,900kg/m³sourcepart density (ISO 3369, not labelled min or typical), EOS M 290, 40 µm FlexLine |
| Strength to weight | 75.4kN·m/kg12% higher | 67.1kN·m/kg |
| Stiffness to weight | 3.08MN·m/kg | 23.4MN·m/kg7.61x higher |
| Poisson's ratio | 0.38sourcetypical | 0.3sourcebase material: austenitic stainless steels incl. 1.4404 (316L), design value |
| Shear modulus | 1.45GPa | 71.2GPa49.1x stiffer in shear |
| Bulk modulus | 5.56GPa | 154GPa |
| Speed of sound | 1,754m/s | 4,839m/s |
| Thermal | ||
| Thermal conductivity | 0.29W/m·Ksourcetypical, average, 23 C | 16.2W/m·Ksourcebase material: wrought 316/316L (Cleveland-Cliffs), at 100 °C |
| Thermal expansion | 55µm/m·Ksourceaverage of flow/cross-flow, below Tg (<143 C) | 15.7µm/m·Ksourcemean 25-100 °C, ASTM E228 |
| 100 mm part over a 50 °C swing | 275µm growth | 78.6µm growth3.5x less |
| Specific heat | 2,200J/kg·Ksourcetypical, 23 °C, DSC (Victrex PEEK 450G TDS, revision Jul 2012) | 500J/kg·Ksourcebase material: wrought 316/316L (Cleveland-Cliffs), 0-100 °C |
| Heats up and cools (diffusivity) | 0.101mm²/s | 4.1mm²/s40.4x faster |
| Thermal shock resistance | 80.1W/m | 2,067W/m25.8x more resistant |
| Melting point | 343°Csourcetypical, DSC | not sourced |
| Glass transition | 143°Csourceonset (midpoint 150 C) | not sourced |
| Max service temperature | 240°CsourceUL 746B RTI, mechanical strength (continuous use index) | not sourced |
| Values for | Victrex PEEK 450G (unreinforced, injection moulded), Victrex TDS rev. March 2026; Poisson from Victrex fluid-management flyer (2020-07) | EOS StainlessSteel 316L (powder 9011-0032), EOS M 290, ParameterSet 316L 20µm Surface M290/400W, as manufactured, horizontal; ISO 6892-1 |
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.
DMLS 316L Stainless Steel is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Is Plastic PEEK stronger than DMLS 316L Stainless Steel?
DMLS 316L Stainless Steel is stronger: its yield strength is 530 MPa against 98 MPa for Plastic PEEK (5.41x).
Which is lighter, Plastic PEEK or DMLS 316L Stainless Steel?
Plastic PEEK is lighter: 1,300 kg/m³ against 7,900 kg/m³ for DMLS 316L Stainless Steel.
Which is stiffer, Plastic PEEK or DMLS 316L Stainless Steel?
DMLS 316L Stainless Steel is stiffer: Young's modulus 185 GPa against 4 GPa for Plastic PEEK, so the same part in DMLS 316L Stainless Steel deflects less under the same load.
Which is lighter for the same job, Plastic PEEK or DMLS 316L Stainless Steel?
For the same stiffness or strength: Plastic PEEK is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; DMLS 316L Stainless Steel is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic PEEK | DMLS 316L Stainless Steel |
|---|---|---|
| Stiff rod or tie (tension) | 7.61x heavier | lighter |
| Stiff beam (bending) | 12% heavier | lighter |
| Stiff panel or plate | lighter | 1.69x heavier |
| Strong rod or tie | lighter | 12% heavier |
| Strong beam | lighter | 1.97x heavier |
| Strong panel or plate | lighter | 2.61x 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 PEEK or DMLS 316L Stainless Steel?
DMLS 316L Stainless Steel conducts heat better: 16.2 W/m·K against 0.29 W/m·K for Plastic PEEK.
Which expands less with temperature?
DMLS 316L Stainless Steel expands less: 15.7 µm/m·K against 55 µm/m·K for Plastic PEEK.