Aluminum 6061-T6 vs. Steel

Compare Aluminum 6061-T6 vs. Steel strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	276MPasourcetypical, 0.2% offset, .500 in dia specimen	385MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey), as reported by AISC
Ultimate tensile strength	310MPasourcetypical	505MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey)
Elongation at break	17%sourcetypical, in 4D, 0.500 in dia specimen	not sourced
Young's modulus (stiffness)	68.3GPasourcetypical	200GPasourcedesign value (AISC 360-16)
Density	2,700kg/m³sourcenominal	7,850kg/m³sourcenominal (constructional data)
Strength to weight	102kN·m/kg2.08x higher	49kN·m/kg
Stiffness to weight	25.3MN·m/kg	25.5MN·m/kg
Poisson's ratio	0.33sourcetypical (handbook physical constant)	0.3sourcedesign value (AISC 360-16 Commentary)
Shear modulus	25.7GPa	76.9GPa3x stiffer in shear
Bulk modulus	67GPa	167GPa
Speed of sound	5,030m/s	5,048m/s
Thermal
Thermal conductivity	167W/m·Ksourcetypical, 20 °C	48W/m·Ksourcenominal at 20 °C
Thermal expansion	23.6µm/m·Ksourcetypical, mean 20-100 °C	12µm/m·Ksourcenominal (constructional data, no temperature range stated)
100 mm part over a 50 °C swing	118µm growth	60µm growth1.97x less
Specific heat	896J/kg·Ksourcetypical, at 100 °C	460–480J/kg·Ksourcebase material: EN S275JR unalloyed structural steel (the EN counterpart of A36), typical, 50/100 °C
Heats up and cools (diffusivity)	69mm²/s5.31x faster	13mm²/s
Thermal shock resistance	19,159W/m3.55x more resistant	5,390W/m
Melting point	582–652°Csourcesolidus-liquidus	not sourced
Values for	6061-T6/T651, Kaiser Aluminum typical properties; Poisson from MIL-HDBK-5J	Generic structural steel, cited as ASTM A992 (the current US structural grade): ASTM A992 W-shapes; Fy/Fu specified minimums from AISC publications (AISC 360-16 Commentary; Modern Steel Construction); elastic constants AISC 360; physical constants from the bauforumstahl structural-steel EPD, which names A992 among covered product standards.

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 6061-T6 stronger than Steel?

Steel is stronger: its yield strength is 385 MPa against 276 MPa for Aluminum 6061-T6 (39%).

Which is lighter, Aluminum 6061-T6 or Steel?

Aluminum 6061-T6 is lighter: 2,700 kg/m³ against 7,850 kg/m³ for Steel.

Which is stiffer, Aluminum 6061-T6 or Steel?

Steel is stiffer: Young's modulus 200 GPa against 68.3 GPa for Aluminum 6061-T6, so the same part in Steel deflects less under the same load.

Which is lighter for the same job, Aluminum 6061-T6 or Steel?

For the same stiffness or strength: Aluminum 6061-T6 is lighter for a stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.

Part that must be	Aluminum 6061-T6	Steel
Stiff rod or tie (tension)	about equal	about equal
Stiff beam (bending)	lighter	1.7x heavier
Stiff panel or plate	lighter	2.03x heavier
Strong rod or tie	lighter	2.08x heavier
Strong beam	lighter	2.33x heavier
Strong panel or plate	lighter	2.46x 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 6061-T6 or Steel?

Aluminum 6061-T6 conducts heat better: 167 W/m·K against 48 W/m·K for Steel.

Which expands less with temperature?

Steel expands less: 12 µm/m·K against 23.6 µm/m·K for Aluminum 6061-T6.

Among 72 materials

Stiffness against density

Strength against density