Materials / Compare
Aluminum vs. Stainless 304
Compare Aluminum vs. Stainless 304 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 | 276MPasourcetypical, 0.2% offset, .500 in dia specimen | 241MPasourcetypical, annealed, 70 °F (21 °C) |
| Ultimate tensile strength | 310MPasourcetypical | 586MPasourcetypical, annealed, 70 °F (21 °C) |
| Elongation at break | 17%sourcetypical, in 4D, 0.500 in dia specimen | 55%sourcetypical, annealed, in 2 in. (50.8 mm) |
| Young's modulus (stiffness) | 68.3GPasourcetypical | 193GPasourcetypical, in tension |
| Density | 2,700kg/m³sourcenominal | 8,030kg/m³sourcetypical |
| Strength to weight | 102kN·m/kg3.41x higher | 30kN·m/kg |
| Stiffness to weight | 25.3MN·m/kg5% higher | 24MN·m/kg |
| Poisson's ratio | 0.33sourcetypical (handbook physical constant) | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 25.7GPa | 74.2GPa2.89x stiffer in shear |
| Bulk modulus | 67GPa | 161GPa |
| Speed of sound | 5,030m/s | 4,903m/s |
| Thermal | ||
| Thermal conductivity | 167W/m·Ksourcetypical, 20 °C | 16.2W/m·Ksourceat 100 °C |
| Thermal expansion | 23.6µm/m·Ksourcetypical, mean 20-100 °C | 16.9µm/m·Ksourcemean, 0–100 °C |
| 100 mm part over a 50 °C swing | 118µm growth | 84.5µm growth40% less |
| Specific heat | 896J/kg·Ksourcetypical, at 100 °C | 500J/kg·Ksourcemean, 0–100 °C |
| Heats up and cools (diffusivity) | 69mm²/s17.1x faster | 4.03mm²/s |
| Thermal shock resistance | 19,159W/m22.9x more resistant | 838W/m |
| Melting point | 582–652°Csourcesolidus-liquidus | 1,399–1,454°Csourcemelting range |
| Max service temperature | not sourced | 899°Csourcecontinuous, oxidation (scaling) limit in air |
| Values for | 6061-T6/T651, Kaiser Aluminum typical properties (sheet, coil & plate datasheet); Poisson from MIL-HDBK-5J | Type 304, annealed flat-rolled (Cleveland-Cliffs 304/304L Product Data Bulletin, May 2021); Poisson's ratio from the Nickel Institute/SCI structural stainless design manual |
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 Aluminum stronger than Stainless 304?
Aluminum is stronger: its yield strength is 276 MPa against 241 MPa for Stainless 304 (15%).
Which is lighter, Aluminum or Stainless 304?
Aluminum is lighter: 2,700 kg/m³ against 8,030 kg/m³ for Stainless 304.
Which is stiffer, Aluminum or Stainless 304?
Stainless 304 is stiffer: Young's modulus 193 GPa against 68.3 GPa for Aluminum, so the same part in Stainless 304 deflects less under the same load.
Which is lighter for the same job, Aluminum or Stainless 304?
For the same stiffness or strength: Aluminum is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Aluminum | Stainless 304 |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 5% heavier |
| Stiff beam (bending) | lighter | 1.77x heavier |
| Stiff panel or plate | lighter | 2.1x heavier |
| Strong rod or tie | lighter | 3.41x heavier |
| Strong beam | lighter | 3.26x heavier |
| Strong panel or plate | lighter | 3.18x 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, Aluminum or Stainless 304?
Aluminum conducts heat better: 167 W/m·K against 16.2 W/m·K for Stainless 304.
Which expands less with temperature?
Stainless 304 expands less: 16.9 µm/m·K against 23.6 µm/m·K for Aluminum.