Aluminum 7075-T6 vs. Nickel Inconel 718

Compare Aluminum 7075-T6 vs. Nickel Inconel 718 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	1,207MPasourcetypical, 1.0 in. hot-rolled bar, 0.2% offset
Ultimate tensile strength	572MPasourcetypical	1,389MPasourcetypical, 1.0 in. bar
Elongation at break	11%sourcetypical, in 4D	20%sourcetypical, 1.0 in. bar
Young's modulus (stiffness)	71GPasourcetypical	200GPasourcetypical, 21 °C, annealed + aged
Density	2,800kg/m³sourcenominal	8,221kg/m³sourcenominal, annealed and aged
Strength to weight	180kN·m/kg22% higher	147kN·m/kg
Stiffness to weight	25.4MN·m/kg4% higher	24.3MN·m/kg
Poisson's ratio	0.33sourcetypical (handbook physical constant)	0.294sourcetypical, 21 °C, annealed + aged
Shear modulus	26.7GPa	77.3GPa2.9x stiffer in shear
Bulk modulus	69.6GPa	162GPa
Speed of sound	5,036m/s	4,932m/s
Thermal
Thermal conductivity	130W/m·Ksourcetypical, 20 °C, T651	11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a)
Thermal expansion	23.4µm/m·Ksourcetypical, mean 20-100 °C	13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged
100 mm part over a 50 °C swing	117µm growth	66µm growth1.77x less
Specific heat	960J/kg·Ksourcetypical, at 100 °C	435J/kg·Ksourcetypical, 21 °C
Heats up and cools (diffusivity)	48.4mm²/s15.2x faster	3.19mm²/s
Thermal shock resistance	26,370W/m7.17x more resistant	3,680W/m
Melting point	532–635°Csourcemelting range	1,260–1,336°Csourcemelting range
Max service temperature	not sourced	704°Csourceupper use temperature stated by producer
Values for	7075-T6/T651, Kaiser Aluminum rod & bar (mechanical) and sheet/coil/plate (physical) typical datasheets; Poisson from MIL-HDBK-5J	INCONEL alloy 718, standard grade, 1750 °F/1 hr anneal + 1325 °F/8 hr F.C. to 1150 °F aged; Special Metals bulletin SMC-045 typical values

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 Nickel Inconel 718?

Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 503 MPa for Aluminum 7075-T6 (2.4x).

Which is lighter, Aluminum 7075-T6 or Nickel Inconel 718?

Aluminum 7075-T6 is lighter: 2,800 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.

Which is stiffer, Aluminum 7075-T6 or Nickel Inconel 718?

Nickel Inconel 718 is stiffer: Young's modulus 200 GPa against 71 GPa for Aluminum 7075-T6, so the same part in Nickel Inconel 718 deflects less under the same load.

Which is lighter for the same job, Aluminum 7075-T6 or Nickel Inconel 718?

For the same stiffness or strength: Aluminum 7075-T6 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 7075-T6	Nickel Inconel 718
Stiff rod or tie (tension)	lighter	4% heavier
Stiff beam (bending)	lighter	1.75x heavier
Stiff panel or plate	lighter	2.08x heavier
Strong rod or tie	lighter	22% heavier
Strong beam	lighter	1.64x heavier
Strong panel or plate	lighter	1.9x 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 Nickel Inconel 718?

Aluminum 7075-T6 conducts heat better: 130 W/m·K against 11.4 W/m·K for Nickel Inconel 718.

Which expands less with temperature?

Nickel Inconel 718 expands less: 13.2 µm/m·K against 23.4 µm/m·K for Aluminum 7075-T6.

Among 59 materials

Stiffness against density

Strength against density