Materials / Compare
Plastic Nylon PA66 vs. Steel AISI 1018
Compare Plastic Nylon PA66 vs. Steel AISI 1018 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 | 85MPasourcetypical, dry | 372MPasourceproducer-stated, cold drawn |
| Ultimate tensile strength | not sourced | 441MPasourceproducer-stated, cold drawn |
| Elongation at break | 30%sourcenominal strain at break, dry | 15%sourcein 2 in (50.8 mm) |
| Young's modulus (stiffness) | 3GPasourcetypical, dry | 200GPasourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Density | 1,130kg/m³sourcetypical | 7,861kg/m³sourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Strength to weight | 75.2kN·m/kg1.59x higher | 47.3kN·m/kg |
| Stiffness to weight | 2.65MN·m/kg | 25.4MN·m/kg9.58x higher |
| Poisson's ratio | 0.4sourcebase material: unfilled polyamide (PA), conditioned, maker design-guide family value (Covestro Table 3-1) | 0.32sourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Shear modulus | 1.07GPa | 75.7GPa70.7x stiffer in shear |
| Bulk modulus | 5GPa | 185GPa |
| Speed of sound | 1,629m/s | 5,043m/s |
| Thermal | ||
| Thermal conductivity | 0.33W/m·Ksourcetypical | 51.9W/m·Ksourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Thermal expansion | 98µm/m·Ksourcelongitudinal, 23-55 °C | 12µm/m·Ksourcebase material: unalloyed carbon steel, Ovako family table (S275JR, 'none alloyed structural steels', C <= 0.21%); mean 20-300 °C |
| 100 mm part over a 50 °C swing | 490µm growth | 60µm growth8.17x less |
| Specific heat | 1,700J/kg·Ksourcetypical | 486J/kg·Ksourcebase material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018) |
| Heats up and cools (diffusivity) | 0.172mm²/s | 13.6mm²/s79.1x faster |
| Thermal shock resistance | 57.2W/m | 5,473W/m95.6x more resistant |
| Melting point | 260°CsourceDSC | not sourced |
| Max service temperature | 101°CsourceIEC 60216 temperature index, 20000 h | not sourced |
| Values for | BASF Ultramid A3K (PA66, unreinforced injection-moulding grade), Product Information 02/2026, dry values (ISO methods) | AISI 1018 cold drawn bar (Niagara LaSalle, cold-finished bar producer) |
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 Nylon PA66 stronger than Steel AISI 1018?
Steel AISI 1018 is stronger: its yield strength is 372 MPa against 85 MPa for Plastic Nylon PA66 (4.38x).
Which is lighter, Plastic Nylon PA66 or Steel AISI 1018?
Plastic Nylon PA66 is lighter: 1,130 kg/m³ against 7,861 kg/m³ for Steel AISI 1018.
Which is stiffer, Plastic Nylon PA66 or Steel AISI 1018?
Steel AISI 1018 is stiffer: Young's modulus 200 GPa against 3 GPa for Plastic Nylon PA66, so the same part in Steel AISI 1018 deflects less under the same load.
Which is lighter for the same job, Plastic Nylon PA66 or Steel AISI 1018?
For the same stiffness or strength: Plastic Nylon PA66 is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Steel AISI 1018 is lighter for a stiff rod or tie (tension), stiff beam (bending).
| Part that must be | Plastic Nylon PA66 | Steel AISI 1018 |
|---|---|---|
| Stiff rod or tie (tension) | 9.58x heavier | lighter |
| Stiff beam (bending) | 17% heavier | lighter |
| Stiff panel or plate | lighter | 1.72x heavier |
| Strong rod or tie | lighter | 1.59x heavier |
| Strong beam | lighter | 2.6x heavier |
| Strong panel or plate | lighter | 3.33x 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 Nylon PA66 or Steel AISI 1018?
Steel AISI 1018 conducts heat better: 51.9 W/m·K against 0.33 W/m·K for Plastic Nylon PA66.
Which expands less with temperature?
Steel AISI 1018 expands less: 12 µm/m·K against 98 µm/m·K for Plastic Nylon PA66.