Materials / Compare
Aluminum vs. Stainless 17-4PH
Compare Aluminum vs. Stainless 17-4PH 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 | 1,275MPasourcetypical, transverse, sheet/strip |
| Ultimate tensile strength | 310MPasourcetypical | 1,379MPasourcetypical, transverse, sheet/strip |
| Elongation at break | 17%sourcetypical, in 4D, 0.500 in dia specimen | 9%sourcetypical, transverse, in 2 in. (50.8 mm) |
| Young's modulus (stiffness) | 68.3GPasourcetypical | 197GPasourceH 900 |
| Density | 2,700kg/m³sourcenominal | 7,800kg/m³sourceH 900 |
| Strength to weight | 102kN·m/kg | 163kN·m/kg1.6x higher |
| Stiffness to weight | 25.3MN·m/kg | 25.3MN·m/kg |
| Poisson's ratio | 0.33sourcetypical (handbook physical constant) | 0.272sourceH 900 (column) |
| Shear modulus | 25.7GPa | 77.4GPa3.02x stiffer in shear |
| Bulk modulus | 67GPa | 144GPa |
| Speed of sound | 5,030m/s | 5,026m/s |
| Thermal | ||
| Thermal conductivity | 167W/m·Ksourcetypical, 20 °C | 17.9W/m·Ksourceat 149 °C (300 °F), H 900 |
| Thermal expansion | 23.6µm/m·Ksourcetypical, mean 20-100 °C | 10.8µm/m·Ksourcemean, 21–93 °C (70–200 °F), H 900 |
| 100 mm part over a 50 °C swing | 118µm growth | 54µm growth2.19x less |
| Specific heat | 896J/kg·Ksourcetypical, at 100 °C | 460J/kg·Ksourcemean, 0–100 °C, H 900 |
| Heats up and cools (diffusivity) | 69mm²/s13.8x faster | 4.99mm²/s |
| Thermal shock resistance | 19,159W/m2.45x more resistant | 7,809W/m |
| Melting point | 582–652°Csourcesolidus-liquidus | not sourced |
| Max service temperature | not sourced | 316°Csourcestrength-retention limit (not oxidation) |
| Values for | 6061-T6/T651, Kaiser Aluminum typical properties (sheet, coil & plate datasheet); Poisson from MIL-HDBK-5J | Cleveland-Cliffs 17-4 PH, Condition H 900, sheet/strip, transverse (Product Data Bulletin, May 2021) |
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 17-4PH?
Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 276 MPa for Aluminum (4.62x).
Which is lighter, Aluminum or Stainless 17-4PH?
Aluminum is lighter: 2,700 kg/m³ against 7,800 kg/m³ for Stainless 17-4PH.
Which is stiffer, Aluminum or Stainless 17-4PH?
Stainless 17-4PH is stiffer: Young's modulus 197 GPa against 68.3 GPa for Aluminum, so the same part in Stainless 17-4PH deflects less under the same load.
Which is lighter for the same job, Aluminum or Stainless 17-4PH?
For the same stiffness or strength: Aluminum is lighter for a stiff beam (bending), stiff panel or plate, strong beam, strong panel or plate; Stainless 17-4PH is lighter for a strong rod or tie.
| Part that must be | Aluminum | Stainless 17-4PH |
|---|---|---|
| Stiff rod or tie (tension) | about equal | about equal |
| Stiff beam (bending) | lighter | 1.7x heavier |
| Stiff panel or plate | lighter | 2.03x heavier |
| Strong rod or tie | 1.6x heavier | lighter |
| Strong beam | lighter | 4% heavier |
| Strong panel or plate | lighter | 34% 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 17-4PH?
Aluminum conducts heat better: 167 W/m·K against 17.9 W/m·K for Stainless 17-4PH.
Which expands less with temperature?
Stainless 17-4PH expands less: 10.8 µm/m·K against 23.6 µm/m·K for Aluminum.