Aluminum 6061-T6 vs. Stainless 17-4PH

Compare Aluminum 6061-T6 vs. Stainless 17-4PH strength, stiffness, weight and thermal properties.

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Mechanical
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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; 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 6061-T6 stronger than Stainless 17-4PH?

Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 276 MPa for Aluminum 6061-T6 (4.62x).

Which is lighter, Aluminum 6061-T6 or Stainless 17-4PH?

Aluminum 6061-T6 is lighter: 2,700 kg/m³ against 7,800 kg/m³ for Stainless 17-4PH.

Which is stiffer, Aluminum 6061-T6 or Stainless 17-4PH?

Stainless 17-4PH is stiffer: Young's modulus 197 GPa against 68.3 GPa for Aluminum 6061-T6, so the same part in Stainless 17-4PH deflects less under the same load.

Which is lighter for the same job, Aluminum 6061-T6 or Stainless 17-4PH?

For the same stiffness or strength: Aluminum 6061-T6 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 6061-T6	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 6061-T6 or Stainless 17-4PH?

Aluminum 6061-T6 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 6061-T6.

Among 59 materials

Stiffness against density

Strength against density