Aluminum 6063-T6 vs. Aluminum 7075-T6

Compare Aluminum 6063-T6 vs. Aluminum 7075-T6 strength, stiffness, weight and thermal properties.

Mechanical	Aluminum 6063-T6	Aluminum 7075-T6
Yield strength	215MPa1	503MPa22.34x stronger
Ultimate tensile strength	240MPa1	572MPa22.38x stronger
Elongation at break	12%1	11%2
Young's modulus (stiffness)	69GPa1	71GPa2
Density	2,700kg/m³1	2,800kg/m³3
Strength to weight	79.6kN·m/kg	180kN·m/kg2.26x higher
Stiffness to weight	25.6MN·m/kg	25.4MN·m/kg
Poisson's ratio	not sourced	0.334
Shear modulus	not sourced	26.7GPa
Bulk modulus	not sourced	69.6GPa
Speed of sound	5,055m/s	5,036m/s

Stiffness against densityHigher and further left: stiffer for its weight

Strength against densityHigher and further left: stronger for its weight

Thermal	Aluminum 6063-T6	Aluminum 7075-T6
Thermal conductivity	201W/m·K11.55x more heat through a fin	130W/m·K3
Thermal expansion	23.4µm/m·K1	23.4µm/m·K3
100 mm part over a 50 °C swing	117µm growth	117µm growth
Specific heat	901J/kg·K5	960J/kg·K3
Heats up and cools (diffusivity)	82.6mm²/s1.71x faster	48.4mm²/s
Thermal shock resistance	not sourced	26,370W/m
Melting point	melting range615–655°C1	melting range532–635°C3

Thermal conductivity against densityHigher and further left: spreads more heat for its weight

Thermal expansion against thermal conductivityLower and further right: warps less when heated

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Sources5 documents: Kaiser Aluminum, U.S. Department of Defense, Hydro

Aluminum 6063-T6: 6063-T6 extruded tube, Kaiser Aluminum Tube & Pipe Alloy 6063 Technical Data (Rev. 05/06), typical properties; specific heat from Hydro EN AW-6063 extruded-products datasheet (Rev.4, 03/2023).
Aluminum 7075-T6: 7075-T6/T651, Kaiser Aluminum rod & bar (mechanical) and sheet/coil/plate (physical) typical datasheets; Poisson from MIL-HDBK-5J

1
Alloy 6063 Tube & Pipe Technical Data, Rev. 05/06Kaiser Aluminumarchived copyAluminum 6063-T6 · Yield strength: typical, T6, 0.0625 in specimenAluminum 6063-T6 · Ultimate tensile strength: typical, T6Aluminum 6063-T6 · Elongation at break: typical, T6, in 4DAluminum 6063-T6 · Young's modulus (stiffness): typicalAluminum 6063-T6 · Density: nominal, 20 °CAluminum 6063-T6 · Thermal conductivity: typical, T6, 20 °CAluminum 6063-T6 · Thermal expansion: typical, mean 20-100 °CAluminum 6063-T6 · Melting point: melting range
2
Alloy 7075 Rod & Bar Technical DataKaiser Aluminumarchived copyAluminum 7075-T6 · Yield strength: typical, 0.2% offset, .500 in dia specimenAluminum 7075-T6 · Ultimate tensile strength: typicalAluminum 7075-T6 · Elongation at break: typical, in 4DAluminum 7075-T6 · Young's modulus (stiffness): typical
3
Alloy 7075 Sheet, Coil & Plate Technical DataKaiser Aluminumarchived copyAluminum 7075-T6 · Density: nominalAluminum 7075-T6 · Thermal conductivity: typical, 20 °C, T651Aluminum 7075-T6 · Thermal expansion: typical, mean 20-100 °CAluminum 7075-T6 · Specific heat: typical, at 100 °CAluminum 7075-T6 · Melting point: melting range
4
MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures (2003)U.S. Department of DefenseAluminum 7075-T6 · Poisson's ratio: typical (handbook physical constant)
5
Technical Datasheet, Extruded Products: Alloy EN AW-6063 (Rev. 4, 2023)Hydroarchived copyAluminum 6063-T6 · Specific heat: typical, 20 °C (Hydro EN AW-6063)

Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

Mechanical

Is Aluminum 6063-T6 stronger than Aluminum 7075-T6?

Aluminum 7075-T6 is stronger: its yield strength is 503 MPa against 215 MPa for Aluminum 6063-T6 (2.34x).

Which is lighter, Aluminum 6063-T6 or Aluminum 7075-T6?

Aluminum 6063-T6 is lighter: 2,700 kg/m³ against 2,800 kg/m³ for Aluminum 7075-T6.

Which is stiffer, Aluminum 6063-T6 or Aluminum 7075-T6?

Aluminum 7075-T6 is stiffer: Young's modulus 71 GPa against 69 GPa for Aluminum 6063-T6, so the same part in Aluminum 7075-T6 deflects less under the same load.

Which is lighter for the same job, Aluminum 6063-T6 or Aluminum 7075-T6?

For the same stiffness or strength: Aluminum 6063-T6 is lighter for a stiff beam (bending), stiff panel or plate; Aluminum 7075-T6 is lighter for a strong rod or tie, strong beam, strong panel or plate.

Part that must be	Aluminum 6063-T6	Aluminum 7075-T6
Stiff rod or tie (tension)	about equal	about equal
Stiff beam (bending)	lighter	2% heavier
Stiff panel or plate	lighter	3% heavier
Strong rod or tie	2.26x heavier	lighter
Strong beam	1.7x heavier	lighter
Strong panel or plate	47% heavier	lighter

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).

Thermal

Which conducts heat better, Aluminum 6063-T6 or Aluminum 7075-T6?

Aluminum 6063-T6 conducts heat better: 201 W/m·K against 130 W/m·K for Aluminum 7075-T6.

Which expands less with temperature?

Aluminum 6063-T6 expands less: 23.4 µm/m·K against 23.4 µm/m·K for Aluminum 7075-T6.