Aluminum 7075-T6 vs. Stainless 17-4PH

Compare Aluminum 7075-T6 vs. Stainless 17-4PH strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	503MPasourcetypical, 0.2% offset, .500 in dia specimen	1,275MPasourcetypical, transverse, sheet/strip
Ultimate tensile strength	572MPasourcetypical	1,379MPasourcetypical, transverse, sheet/strip
Elongation at break	11%sourcetypical, in 4D	9%sourcetypical, transverse, in 2 in. (50.8 mm)
Young's modulus (stiffness)	71GPasourcetypical	197GPasourceH 900
Density	2,800kg/m³sourcenominal	7,800kg/m³sourceH 900
Strength to weight	180kN·m/kg10% higher	163kN·m/kg
Stiffness to weight	25.4MN·m/kg	25.3MN·m/kg
Poisson's ratio	0.33sourcetypical (handbook physical constant)	0.272sourceH 900 (column)
Shear modulus	26.7GPa	77.4GPa2.9x stiffer in shear
Bulk modulus	69.6GPa	144GPa
Speed of sound	5,036m/s	5,026m/s
Thermal
Thermal conductivity	130W/m·Ksourcetypical, 20 °C, T651	17.9W/m·Ksourceat 149 °C (300 °F), H 900
Thermal expansion	23.4µm/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	117µm growth	54µm growth2.17x less
Specific heat	960J/kg·Ksourcetypical, at 100 °C	460J/kg·Ksourcemean, 0–100 °C, H 900
Heats up and cools (diffusivity)	48.4mm²/s9.69x faster	4.99mm²/s
Thermal shock resistance	26,370W/m3.38x more resistant	7,809W/m
Melting point	532–635°Csourcemelting range	not sourced
Max service temperature	not sourced	316°Csourcestrength-retention limit (not oxidation)
Values for	7075-T6/T651, Kaiser Aluminum rod & bar (mechanical) and sheet/coil/plate (physical) typical datasheets; 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 7075-T6 stronger than Stainless 17-4PH?

Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 503 MPa for Aluminum 7075-T6 (2.53x).

Which is lighter, Aluminum 7075-T6 or Stainless 17-4PH?

Aluminum 7075-T6 is lighter: 2,800 kg/m³ against 7,800 kg/m³ for Stainless 17-4PH.

Which is stiffer, Aluminum 7075-T6 or Stainless 17-4PH?

Stainless 17-4PH is stiffer: Young's modulus 197 GPa against 71 GPa for Aluminum 7075-T6, so the same part in Stainless 17-4PH deflects less under the same load.

Which is lighter for the same job, Aluminum 7075-T6 or Stainless 17-4PH?

For the same stiffness or strength: Aluminum 7075-T6 is lighter for a stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	Aluminum 7075-T6	Stainless 17-4PH
Stiff rod or tie (tension)	about equal	about equal
Stiff beam (bending)	lighter	1.67x heavier
Stiff panel or plate	lighter	1.98x heavier
Strong rod or tie	lighter	10% heavier
Strong beam	lighter	50% heavier
Strong panel or plate	lighter	1.75x 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 7075-T6 or Stainless 17-4PH?

Aluminum 7075-T6 conducts heat better: 130 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 23.4 µm/m·K for Aluminum 7075-T6.

Among 59 materials

Stiffness against density

Strength against density