Aluminum A380 vs. Steel AISI 1045

Compare Aluminum A380 vs. Steel AISI 1045 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	160MPasourcetypical, 25 °C	531MPasourceproducer-stated, cold drawn
Ultimate tensile strength	320MPasourcetypical, 25 °C	627MPasourceproducer-stated, cold drawn
Elongation at break	3.5%sourcetypical	12%sourcein 2 in (50.8 mm)
Young's modulus (stiffness)	71GPasourcetypical, 25 °C	210GPasourcetypical
Density	2,713kg/m³sourcetypical at 68 °F	7,800kg/m³sourcetypical
Strength to weight	59kN·m/kg	68.1kN·m/kg15% higher
Stiffness to weight	26.2MN·m/kg	26.9MN·m/kg3% higher
Poisson's ratio	not sourced	0.3sourcetypical
Shear modulus	not sourced	80.8GPa
Bulk modulus	not sourced	175GPa
Speed of sound	5,116m/s	5,189m/s
Thermal
Thermal conductivity	96.2W/m·Ksourcetypical at 68 °F	40–45W/m·Ksourcetypical range, ambient
Thermal expansion	21.8µm/m·Ksourcetypical, 68-572 °F (20-300 °C)	12µm/m·Ksourcetypical, mean 20-300 °C
100 mm part over a 50 °C swing	109µm growth	60µm growth1.82x less
Specific heat	963J/kg·Ksourcetypical at 68 °F	460–480J/kg·Ksourcetypical range, 50/100 °C
Heats up and cools (diffusivity)	36.8mm²/s3.18x faster	11.6mm²/s
Thermal shock resistance	not sourced	6,269W/m
Values for	A380 aluminium high-pressure die-casting alloy, typical properties; Rheocast Company (aluminium die caster, Germantown WI) A380 alloy data page.	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 A380 stronger than Steel AISI 1045?

Steel AISI 1045 is stronger: its yield strength is 531 MPa against 160 MPa for Aluminum A380 (3.32x).

Which is lighter, Aluminum A380 or Steel AISI 1045?

Aluminum A380 is lighter: 2,713 kg/m³ against 7,800 kg/m³ for Steel AISI 1045.

Which is stiffer, Aluminum A380 or Steel AISI 1045?

Steel AISI 1045 is stiffer: Young's modulus 210 GPa against 71 GPa for Aluminum A380, so the same part in Steel AISI 1045 deflects less under the same load.

Which is lighter for the same job, Aluminum A380 or Steel AISI 1045?

For the same stiffness or strength: Aluminum A380 is lighter for a stiff beam (bending), stiff panel or plate, strong beam, strong panel or plate; Steel AISI 1045 is lighter for a stiff rod or tie (tension), strong rod or tie.

Part that must be	Aluminum A380	Steel AISI 1045
Stiff rod or tie (tension)	3% heavier	lighter
Stiff beam (bending)	lighter	1.67x heavier
Stiff panel or plate	lighter	2x heavier
Strong rod or tie	15% heavier	lighter
Strong beam	lighter	29% heavier
Strong panel or plate	lighter	1.58x 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 A380 or Steel AISI 1045?

Aluminum A380 conducts heat better: 96.2 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 21.8 µm/m·K for Aluminum A380.

Among 72 materials

Stiffness against density

Strength against density