Aluminum 1100-O vs. Stainless Steel 304

Compare Aluminum 1100-O vs. Stainless Steel 304 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	35MPasourcetypical, O, 0.0625 in specimen	241MPasourcetypical, annealed, 70 °F (21 °C)
Ultimate tensile strength	90MPasourcetypical, O	586MPasourcetypical, annealed, 70 °F (21 °C)
Elongation at break	35%sourcetypical, O, in 4D	55%sourcetypical, annealed, in 2 in. (50.8 mm)
Young's modulus (stiffness)	69GPasourcetypical	193GPasourcetypical, in tension
Density	2,710kg/m³sourcenominal, 20 °C	8,030kg/m³sourcetypical
Strength to weight	12.9kN·m/kg	30kN·m/kg2.32x higher
Stiffness to weight	25.5MN·m/kg6% higher	24MN·m/kg
Poisson's ratio	not sourced	0.3sourcedesign value (structural stainless steels)
Shear modulus	not sourced	74.2GPa
Bulk modulus	not sourced	161GPa
Speed of sound	5,046m/s	4,903m/s
Thermal
Thermal conductivity	222W/m·Ksourcetypical, O, 20 °C	16.2W/m·Ksourceat 100 °C
Thermal expansion	23.6µm/m·Ksourcetypical, mean 20-100 °C	16.9µm/m·Ksourcemean, 0–100 °C
100 mm part over a 50 °C swing	118µm growth	84.5µm growth40% less
Specific heat	901J/kg·Ksourcebase material: commercially pure aluminium EN AW-1050A (Hydro), 20 °C	500J/kg·Ksourcemean, 0–100 °C
Heats up and cools (diffusivity)	90.9mm²/s22.5x faster	4.03mm²/s
Thermal shock resistance	not sourced	838W/m
Melting point	640–655°Csourcemelting range	1,399–1,454°Csourcemelting range
Max service temperature	not sourced	899°Csourcecontinuous, oxidation (scaling) limit in air
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).	Type 304, annealed flat-rolled (Cleveland-Cliffs 304/304L Product Data Bulletin, May 2021); Poisson's ratio from the Nickel Institute/SCI structural stainless design manual

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 Stainless Steel 304?

Stainless Steel 304 is stronger: its yield strength is 241 MPa against 35 MPa for Aluminum 1100-O (6.89x).

Which is lighter, Aluminum 1100-O or Stainless Steel 304?

Aluminum 1100-O is lighter: 2,710 kg/m³ against 8,030 kg/m³ for Stainless Steel 304.

Which is stiffer, Aluminum 1100-O or Stainless Steel 304?

Stainless Steel 304 is stiffer: Young's modulus 193 GPa against 69 GPa for Aluminum 1100-O, so the same part in Stainless Steel 304 deflects less under the same load.

Which is lighter for the same job, Aluminum 1100-O or Stainless Steel 304?

For the same stiffness or strength: Aluminum 1100-O is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong panel or plate; Stainless Steel 304 is lighter for a strong rod or tie, strong beam.

Part that must be	Aluminum 1100-O	Stainless Steel 304
Stiff rod or tie (tension)	lighter	6% heavier
Stiff beam (bending)	lighter	1.77x heavier
Stiff panel or plate	lighter	2.1x heavier
Strong rod or tie	2.32x heavier	lighter
Strong beam	22% heavier	lighter
Strong panel or plate	lighter	13% 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 1100-O or Stainless Steel 304?

Aluminum 1100-O conducts heat better: 222 W/m·K against 16.2 W/m·K for Stainless Steel 304.

Which expands less with temperature?

Stainless Steel 304 expands less: 16.9 µm/m·K against 23.6 µm/m·K for Aluminum 1100-O.

Among 72 materials

Stiffness against density

Strength against density