Materials / Compare
Plastic PETG vs. Steel
Compare Plastic PETG vs. 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 | 46.2MPasourcetypical | 385MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey), as reported by AISC |
| Ultimate tensile strength | 46.2MPasourcetypical, peak stress (= stress at yield) | 505MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey) |
| Flexural strength | 78.9MPasourcetypical | not sourced |
| Elongation at break | 7.6%sourcetypical | not sourced |
| Young's modulus (stiffness) | 1.94GPasourcetypical | 200GPasourcedesign value (AISC 360-16) |
| Density | 1,270kg/m³sourcetypical | 7,850kg/m³sourcenominal (constructional data) |
| Strength to weight | 36.4kN·m/kg | 49kN·m/kg35% higher |
| Stiffness to weight | 1.53MN·m/kg | 25.5MN·m/kg16.7x higher |
| Poisson's ratio | not sourced | 0.3sourcedesign value (AISC 360-16 Commentary) |
| Shear modulus | not sourced | 76.9GPa |
| Bulk modulus | not sourced | 167GPa |
| Speed of sound | 1,236m/s | 5,048m/s |
| Thermal | ||
| Thermal conductivity | 0.21W/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical | 48W/m·Ksourcenominal at 20 °C |
| Thermal expansion | 51µm/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical | 12µm/m·Ksourcenominal (constructional data, no temperature range stated) |
| 100 mm part over a 50 °C swing | 255µm growth | 60µm growth4.25x less |
| Specific heat | 1,300J/kg·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), DSC at 60 °C (lowest temperature listed) | 460–480J/kg·Ksourcebase material: EN S275JR unalloyed structural steel (the EN counterpart of A36), typical, 50/100 °C |
| Heats up and cools (diffusivity) | 0.127mm²/s | 13mm²/s102x faster |
| Thermal shock resistance | not sourced | 5,390W/m |
| Glass transition | 77.4°Csourcetypical | not sourced |
| Max service temperature | 76.2°CsourceHDT 0.455 MPa (printed specimens) | not sourced |
| Values for | Ultimaker PETG, 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 v1.00, April 29, 2022. | Generic structural steel, cited as ASTM A992 (the current US structural grade): ASTM A992 W-shapes; Fy/Fu specified minimums from AISC publications (AISC 360-16 Commentary; Modern Steel Construction); elastic constants AISC 360; physical constants from the bauforumstahl structural-steel EPD, which names A992 among covered product standards. |
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 PETG is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Is Plastic PETG stronger than Steel?
Steel is stronger: its yield strength is 385 MPa against 46.2 MPa for Plastic PETG (8.33x).
Which is lighter, Plastic PETG or Steel?
Plastic PETG is lighter: 1,270 kg/m³ against 7,850 kg/m³ for Steel.
Which is stiffer, Plastic PETG or Steel?
Steel is stiffer: Young's modulus 200 GPa against 1.94 GPa for Plastic PETG, so the same part in Steel deflects less under the same load.
Which is lighter for the same job, Plastic PETG or Steel?
For the same stiffness or strength: Plastic PETG is lighter for a stiff panel or plate, strong beam, strong panel or plate; Steel is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie.
| Part that must be | Plastic PETG | Steel |
|---|---|---|
| Stiff rod or tie (tension) | 16.7x heavier | lighter |
| Stiff beam (bending) | 1.64x heavier | lighter |
| Stiff panel or plate | lighter | 32% heavier |
| Strong rod or tie | 35% heavier | lighter |
| Strong beam | lighter | 1.5x heavier |
| Strong panel or plate | lighter | 2.14x 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 PETG or Steel?
Steel conducts heat better: 48 W/m·K against 0.21 W/m·K for Plastic PETG.
Which expands less with temperature?
Steel expands less: 12 µm/m·K against 51 µm/m·K for Plastic PETG.