Aluminum 1100-O vs. Steel AISI 1045

Compare Aluminum 1100-O vs. Steel AISI 1045 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	35MPasourcetypical, O, 0.0625 in specimen	531MPasourceproducer-stated, cold drawn
Ultimate tensile strength	90MPasourcetypical, O	627MPasourceproducer-stated, cold drawn
Elongation at break	35%sourcetypical, O, in 4D	12%sourcein 2 in (50.8 mm)
Young's modulus (stiffness)	69GPasourcetypical	210GPasourcetypical3.04x stiffer
Density	2,710kg/m³sourcenominal, 20 °C	7,800kg/m³sourcetypical
Strength to weight	12.9kN·m/kg	68.1kN·m/kg5.27x higher
Stiffness to weight	25.5MN·m/kg	26.9MN·m/kg6% higher
Poisson's ratio	not sourced	0.3sourcetypical
Shear modulus	not sourced	80.8GPa
Bulk modulus	not sourced	175GPa
Speed of sound	5,046m/s	5,189m/s
Thermal
Thermal conductivity	222W/m·Ksourcetypical, O, 20 °C	40–45W/m·Ksourcetypical range, ambient
Thermal expansion	23.6µm/m·Ksourcetypical, mean 20-100 °C	12µm/m·Ksourcetypical, mean 20-300 °C
100 mm part over a 50 °C swing	118µm growth	60µm growth1.97x less
Specific heat	901J/kg·Ksourcebase material: commercially pure aluminium EN AW-1050A (Hydro), 20 °C	460–480J/kg·Ksourcetypical range, 50/100 °C
Heats up and cools (diffusivity)	90.9mm²/s7.84x faster	11.6mm²/s
Thermal shock resistance	not sourced	6,269W/m
Melting point	640–655°Csourcemelting range	not sourced
Values for	1100-O (annealed) commercially pure aluminium, Kaiser Aluminum Tube & Pipe Alloy 1100 Technical Data (Rev. 05/06), typical properties; specific heat from Hydro EN AW-1050A (99.5% Al) extruded-products datasheet (10/2018).	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 1100-O stronger than Steel AISI 1045?

Steel AISI 1045 is stronger: its yield strength is 531 MPa against 35 MPa for Aluminum 1100-O (15.2x).

Which is lighter, Aluminum 1100-O or Steel AISI 1045?

Aluminum 1100-O is lighter: 2,710 kg/m³ against 7,800 kg/m³ for Steel AISI 1045.

Which is stiffer, Aluminum 1100-O or Steel AISI 1045?

Steel AISI 1045 is stiffer: Young's modulus 210 GPa against 69 GPa for Aluminum 1100-O, so the same part in Steel AISI 1045 deflects less under the same load.

Which is lighter for the same job, Aluminum 1100-O or Steel AISI 1045?

For the same stiffness or strength: Aluminum 1100-O is lighter for a stiff beam (bending), stiff panel or plate; Steel AISI 1045 is lighter for a stiff rod or tie (tension), strong rod or tie, strong beam, strong panel or plate.

Part that must be	Aluminum 1100-O	Steel AISI 1045
Stiff rod or tie (tension)	6% heavier	lighter
Stiff beam (bending)	lighter	1.65x heavier
Stiff panel or plate	lighter	1.99x heavier
Strong rod or tie	5.27x heavier	lighter
Strong beam	2.13x heavier	lighter
Strong panel or plate	35% 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).

Which conducts heat better, Aluminum 1100-O or Steel AISI 1045?

Aluminum 1100-O conducts heat better: 222 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 23.6 µm/m·K for Aluminum 1100-O.

Among 72 materials

Stiffness against density

Strength against density