Aluminum A380 vs. Stainless Steel 304

Compare Aluminum A380 vs. Stainless Steel 304 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	160MPasourcetypical, 25 °C	241MPasourcetypical, annealed, 70 °F (21 °C)
Ultimate tensile strength	320MPasourcetypical, 25 °C	586MPasourcetypical, annealed, 70 °F (21 °C)
Elongation at break	3.5%sourcetypical	55%sourcetypical, annealed, in 2 in. (50.8 mm)
Young's modulus (stiffness)	71GPasourcetypical, 25 °C	193GPasourcetypical, in tension
Density	2,713kg/m³sourcetypical at 68 °F	8,030kg/m³sourcetypical
Strength to weight	59kN·m/kg1.97x higher	30kN·m/kg
Stiffness to weight	26.2MN·m/kg9% 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	5,116m/s	4,903m/s
Thermal
Thermal conductivity	96.2W/m·Ksourcetypical at 68 °F	16.2W/m·Ksourceat 100 °C
Thermal expansion	21.8µm/m·Ksourcetypical, 68-572 °F (20-300 °C)	16.9µm/m·Ksourcemean, 0–100 °C
100 mm part over a 50 °C swing	109µm growth	84.5µm growth29% less
Specific heat	963J/kg·Ksourcetypical at 68 °F	500J/kg·Ksourcemean, 0–100 °C
Heats up and cools (diffusivity)	36.8mm²/s9.13x faster	4.03mm²/s
Thermal shock resistance	not sourced	838W/m
Melting point	not sourced	1,399–1,454°Csourcemelting range
Max service temperature	not sourced	899°Csourcecontinuous, oxidation (scaling) limit in air
Values for	A380 aluminium high-pressure die-casting alloy, typical properties; Rheocast Company (aluminium die caster, Germantown WI) A380 alloy data page.	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 A380 stronger than Stainless Steel 304?

Stainless Steel 304 is stronger: its yield strength is 241 MPa against 160 MPa for Aluminum A380 (1.51x).

Which is lighter, Aluminum A380 or Stainless Steel 304?

Aluminum A380 is lighter: 2,713 kg/m³ against 8,030 kg/m³ for Stainless Steel 304.

Which is stiffer, Aluminum A380 or Stainless Steel 304?

Stainless Steel 304 is stiffer: Young's modulus 193 GPa against 71 GPa for Aluminum A380, so the same part in Stainless Steel 304 deflects less under the same load.

Which is lighter for the same job, Aluminum A380 or Stainless Steel 304?

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

Part that must be	Aluminum A380	Stainless Steel 304
Stiff rod or tie (tension)	lighter	9% heavier
Stiff beam (bending)	lighter	1.8x heavier
Stiff panel or plate	lighter	2.12x heavier
Strong rod or tie	lighter	1.97x heavier
Strong beam	lighter	2.25x heavier
Strong panel or plate	lighter	2.41x 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 Stainless Steel 304?

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

Among 72 materials

Stiffness against density

Strength against density