JIS ADC12 (Al-Si-Cu, about A383 / EN AC-46100) high-pressure die-casting alloy, as cast; physical properties from Daiki Aluminium Industry (ADC12 ingot producer) measured values; modulus from S.S.Aluminum (ADC12 ingot producer) standard values.
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 ADC12 stronger than Steel?
Steel is stronger: its yield strength is 385 MPa against 149 MPa for Aluminum ADC12 (2.58x).
Which is lighter, Aluminum ADC12 or Steel?
Aluminum ADC12 is lighter: 2,680 kg/m³ against 7,850 kg/m³ for Steel.
Which is stiffer, Aluminum ADC12 or Steel?
Steel is stiffer: Young's modulus 200 GPa against 79.8 GPa for Aluminum ADC12, so the same part in Steel deflects less under the same load.
Which is lighter for the same job, Aluminum ADC12 or Steel?
For the same stiffness or strength: Aluminum ADC12 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 ADC12
Steel
Stiff rod or tie (tension)
lighter
17% heavier
Stiff beam (bending)
lighter
1.85x heavier
Stiff panel or plate
lighter
2.16x heavier
Strong rod or tie
lighter
13% heavier
Strong beam
lighter
1.56x heavier
Strong panel or plate
lighter
1.82x 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 ADC12 or Steel?
Aluminum ADC12 conducts heat better: 125 W/m·K against 48 W/m·K for Steel.
Which expands less with temperature?
Steel expands less: 12 µm/m·K against 21 µm/m·K for Aluminum ADC12.