Aluminum 7050-T7451 vs. Stainless 17-4PH

Compare Aluminum 7050-T7451 vs. Stainless 17-4PH strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	469MPasourcetypical, longitudinal, 0.2% offset	1,275MPasourcetypical, transverse, sheet/strip
Ultimate tensile strength	524MPasourcetypical, longitudinal	1,379MPasourcetypical, transverse, sheet/strip
Elongation at break	11%sourcetypical, longitudinal	9%sourcetypical, transverse, in 2 in. (50.8 mm)
Young's modulus (stiffness)	70.3GPasourcetypical	197GPasourceH 900
Density	2,830kg/m³sourcenominal	7,800kg/m³sourceH 900
Strength to weight	166kN·m/kg1% higher	163kN·m/kg
Stiffness to weight	24.8MN·m/kg	25.3MN·m/kg2% higher
Poisson's ratio	0.33sourcetypical (handbook physical constant)	0.272sourceH 900 (column)
Shear modulus	26.4GPa	77.4GPa2.93x stiffer in shear
Bulk modulus	68.9GPa	144GPa
Speed of sound	4,984m/s	5,026m/s
Thermal
Thermal conductivity	157W/m·Ksourcetypical, 20 °C	17.9W/m·Ksourceat 149 °C (300 °F), H 900
Thermal expansion	23.5µm/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 growth2.18x less
Specific heat	860J/kg·Ksourcetypical, at 100 °C	460J/kg·Ksourcemean, 0–100 °C, H 900
Heats up and cools (diffusivity)	64.5mm²/s12.9x faster	4.99mm²/s
Thermal shock resistance	29,862W/m3.82x more resistant	7,809W/m
Melting point	524–635°Csourcemelting range	not sourced
Max service temperature	not sourced	316°Csourcestrength-retention limit (not oxidation)
Values for	7050-T7451 plate, Kaiser Aluminum sheet, coil & plate typical datasheet (longitudinal); 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 7050-T7451 stronger than Stainless 17-4PH?

Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 469 MPa for Aluminum 7050-T7451 (2.72x).

Which is lighter, Aluminum 7050-T7451 or Stainless 17-4PH?

Aluminum 7050-T7451 is lighter: 2,830 kg/m³ against 7,800 kg/m³ for Stainless 17-4PH.

Which is stiffer, Aluminum 7050-T7451 or Stainless 17-4PH?

Stainless 17-4PH is stiffer: Young's modulus 197 GPa against 70.3 GPa for Aluminum 7050-T7451, so the same part in Stainless 17-4PH deflects less under the same load.

Which is lighter for the same job, Aluminum 7050-T7451 or Stainless 17-4PH?

For the same stiffness or strength: Aluminum 7050-T7451 is lighter for a stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Stainless 17-4PH is lighter for a stiff rod or tie (tension).

Part that must be	Aluminum 7050-T7451	Stainless 17-4PH
Stiff rod or tie (tension)	2% heavier	lighter
Stiff beam (bending)	lighter	1.65x heavier
Stiff panel or plate	lighter	1.95x heavier
Strong rod or tie	lighter	1% heavier
Strong beam	lighter	41% heavier
Strong panel or plate	lighter	1.67x 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 7050-T7451 or Stainless 17-4PH?

Aluminum 7050-T7451 conducts heat better: 157 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 23.5 µm/m·K for Aluminum 7050-T7451.

Among 59 materials

Stiffness against density

Strength against density