Materials / Compare
Plastic Polypropylene vs. Steel AISI 1018
Compare Plastic Polypropylene 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 | 33MPasourcetypical, tensile stress at yield ISO 527 | 372MPasourceproducer-stated, cold drawn |
| Ultimate tensile strength | not sourced | 441MPasourceproducer-stated, cold drawn |
| Elongation at break | not sourced | 15%sourcein 2 in (50.8 mm) |
| Young's modulus (stiffness) | 1.45GPasourcetypical, tensile modulus ISO 527 | 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 | 900kg/m³sourcetypical, 23 °C ISO 1183-1 | 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 | 36.7kN·m/kg | 47.3kN·m/kg29% higher |
| Stiffness to weight | 1.61MN·m/kg | 25.4MN·m/kg15.8x higher |
| Poisson's ratio | 0.42sourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) | 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 | 0.511GPa | 75.7GPa148x stiffer in shear |
| Bulk modulus | 3.02GPa | 185GPa |
| Speed of sound | 1,269m/s | 5,043m/s |
| Thermal | ||
| Thermal conductivity | 0.17–0.22W/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) | 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 | 80–100µm/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene) | 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 | 450µm growth | 60µm growth7.5x less |
| Specific heat | not sourced | 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) | not sourced | 13.6mm²/s |
| Thermal shock resistance | 28.6W/m | 5,473W/m191x more resistant |
| Max service temperature | 90°CsourceHDT 0.45 MPa (ISO 75B), unannealed | not sourced |
| Values for | LyondellBasell Moplen HP501H polypropylene homopolymer (general purpose), typical ISO values | 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 Polypropylene stronger than Steel AISI 1018?
Steel AISI 1018 is stronger: its yield strength is 372 MPa against 33 MPa for Plastic Polypropylene (11.3x).
Which is lighter, Plastic Polypropylene or Steel AISI 1018?
Plastic Polypropylene is lighter: 900 kg/m³ against 7,861 kg/m³ for Steel AISI 1018.
Which is stiffer, Plastic Polypropylene or Steel AISI 1018?
Steel AISI 1018 is stiffer: Young's modulus 200 GPa against 1.45 GPa for Plastic Polypropylene, so the same part in Steel AISI 1018 deflects less under the same load.
Which is lighter for the same job, Plastic Polypropylene or Steel AISI 1018?
For the same stiffness or strength: Plastic Polypropylene is lighter for a stiff panel or plate, strong beam, strong panel or plate; Steel AISI 1018 is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie.
| Part that must be | Plastic Polypropylene | Steel AISI 1018 |
|---|---|---|
| Stiff rod or tie (tension) | 15.8x heavier | lighter |
| Stiff beam (bending) | 34% heavier | lighter |
| Stiff panel or plate | lighter | 1.69x heavier |
| Strong rod or tie | 29% heavier | lighter |
| Strong beam | lighter | 1.74x heavier |
| Strong panel or plate | lighter | 2.6x 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 Polypropylene or Steel AISI 1018?
Steel AISI 1018 conducts heat better: 51.9 W/m·K against 0.195 W/m·K for Plastic Polypropylene.
Which expands less with temperature?
Steel AISI 1018 expands less: 12 µm/m·K against 90 µm/m·K for Plastic Polypropylene.