Materials / Compare
Magnesium AZ91D vs. Steel AISI 1018
Compare Magnesium AZ91D 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 | 150MPasourcetypical, 0.2% tensile yield, ambient temperature | 372MPasourceproducer-stated, cold drawn |
| Ultimate tensile strength | 230MPasourcetypical, ambient temperature | 441MPasourceproducer-stated, cold drawn |
| Elongation at break | 3%sourcetypical, ambient temperature | 15%sourcein 2 in (50.8 mm) |
| Young's modulus (stiffness) | 45GPasourcetypical | 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 | 1,810kg/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 | 82.9kN·m/kg1.75x higher | 47.3kN·m/kg |
| Stiffness to weight | 24.9MN·m/kg | 25.4MN·m/kg2% higher |
| Poisson's ratio | 0.35sourcebase material: AZ91C casting (MIL-HDBK-5J handbook physical constant) | 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 | 16.7GPa | 75.7GPa4.54x stiffer in shear |
| Bulk modulus | 50GPa | 185GPa |
| Speed of sound | 4,986m/s | 5,043m/s |
| Thermal | ||
| Thermal conductivity | 72W/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 | 25µm/m·Ksourcetypical, temperature range not stated | 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 | 125µm growth | 60µm growth2.08x less |
| Specific heat | 1,050J/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) | 37.9mm²/s2.79x faster | 13.6mm²/s |
| Thermal shock resistance | 6,240W/m14% more resistant | 5,473W/m |
| Melting point | 470–595°Csourcemelting range | not sourced |
| Values for | ELEKTRON AZ91D magnesium die-casting alloy, as cast; Magnesium Elektron datasheet 475 (7/01), typical properties; Poisson from MIL-HDBK-5J for AZ91C castings. | 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 Magnesium AZ91D stronger than Steel AISI 1018?
Steel AISI 1018 is stronger: its yield strength is 372 MPa against 150 MPa for Magnesium AZ91D (2.48x).
Which is lighter, Magnesium AZ91D or Steel AISI 1018?
Magnesium AZ91D is lighter: 1,810 kg/m³ against 7,861 kg/m³ for Steel AISI 1018.
Which is stiffer, Magnesium AZ91D or Steel AISI 1018?
Steel AISI 1018 is stiffer: Young's modulus 200 GPa against 45 GPa for Magnesium AZ91D, so the same part in Steel AISI 1018 deflects less under the same load.
Which is lighter for the same job, Magnesium AZ91D or Steel AISI 1018?
For the same stiffness or strength: Magnesium AZ91D is lighter for a stiff beam (bending), 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).
| Part that must be | Magnesium AZ91D | Steel AISI 1018 |
|---|---|---|
| Stiff rod or tie (tension) | 2% heavier | lighter |
| Stiff beam (bending) | lighter | 2.06x heavier |
| Stiff panel or plate | lighter | 2.64x heavier |
| Strong rod or tie | lighter | 1.75x heavier |
| Strong beam | lighter | 2.37x heavier |
| Strong panel or plate | lighter | 2.76x 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, Magnesium AZ91D or Steel AISI 1018?
Magnesium AZ91D conducts heat better: 72 W/m·K against 51.9 W/m·K for Steel AISI 1018.
Which expands less with temperature?
Steel AISI 1018 expands less: 12 µm/m·K against 25 µm/m·K for Magnesium AZ91D.