Aluminum 6063-T6 vs. Steel AISI 1045

Compare Aluminum 6063-T6 vs. Steel AISI 1045 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	215MPasourcetypical, T6, 0.0625 in specimen	531MPasourceproducer-stated, cold drawn
Ultimate tensile strength	240MPasourcetypical, T6	627MPasourceproducer-stated, cold drawn
Elongation at break	12%sourcetypical, T6, in 4D	12%sourcein 2 in (50.8 mm)
Young's modulus (stiffness)	69GPasourcetypical	210GPasourcetypical3.04x stiffer
Density	2,700kg/m³sourcenominal, 20 °C	7,800kg/m³sourcetypical
Strength to weight	79.6kN·m/kg17% higher	68.1kN·m/kg
Stiffness to weight	25.6MN·m/kg	26.9MN·m/kg5% higher
Poisson's ratio	not sourced	0.3sourcetypical
Shear modulus	not sourced	80.8GPa
Bulk modulus	not sourced	175GPa
Speed of sound	5,055m/s	5,189m/s
Thermal
Thermal conductivity	201W/m·Ksourcetypical, T6, 20 °C	40–45W/m·Ksourcetypical range, ambient
Thermal expansion	23.4µm/m·Ksourcetypical, mean 20-100 °C	12µm/m·Ksourcetypical, mean 20-300 °C
100 mm part over a 50 °C swing	117µm growth	60µm growth1.95x less
Specific heat	901J/kg·Ksourcetypical, 20 °C (Hydro EN AW-6063)	460–480J/kg·Ksourcetypical range, 50/100 °C
Heats up and cools (diffusivity)	82.6mm²/s7.13x faster	11.6mm²/s
Thermal shock resistance	not sourced	6,269W/m
Melting point	615–655°Csourcemelting range	not sourced
Values for	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).	AISI 1045 cold drawn bar (Niagara LaSalle) for mechanical; Ovako C45 (lists 'SAE 1045' as a similar designation) for physical constants

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 6063-T6 stronger than Steel AISI 1045?

Steel AISI 1045 is stronger: its yield strength is 531 MPa against 215 MPa for Aluminum 6063-T6 (2.47x).

Which is lighter, Aluminum 6063-T6 or Steel AISI 1045?

Aluminum 6063-T6 is lighter: 2,700 kg/m³ against 7,800 kg/m³ for Steel AISI 1045.

Which is stiffer, Aluminum 6063-T6 or Steel AISI 1045?

Steel AISI 1045 is stiffer: Young's modulus 210 GPa against 69 GPa for Aluminum 6063-T6, so the same part in Steel AISI 1045 deflects less under the same load.

Which is lighter for the same job, Aluminum 6063-T6 or Steel AISI 1045?

For the same stiffness or strength: Aluminum 6063-T6 is lighter for a stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Steel AISI 1045 is lighter for a stiff rod or tie (tension).

Part that must be	Aluminum 6063-T6	Steel AISI 1045
Stiff rod or tie (tension)	5% heavier	lighter
Stiff beam (bending)	lighter	1.66x heavier
Stiff panel or plate	lighter	1.99x heavier
Strong rod or tie	lighter	17% heavier
Strong beam	lighter	1.58x heavier
Strong panel or plate	lighter	1.84x 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 6063-T6 or Steel AISI 1045?

Aluminum 6063-T6 conducts heat better: 201 W/m·K against 42.5 W/m·K for Steel AISI 1045.

Which expands less with temperature?

Steel AISI 1045 expands less: 12 µm/m·K against 23.4 µm/m·K for Aluminum 6063-T6.

Among 72 materials

Stiffness against density

Strength against density