Aluminum ADC12 vs. Stainless Steel 303

Compare Aluminum ADC12 vs. Stainless Steel 303 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	149MPasourceone test result, 0.2% proof stress, as cast, ASTM tensile bar (Daiki)	275MPasourceOutokumpu typical (product P = hot rolled plate, transverse)
Ultimate tensile strength	345MPasourceone test result, as cast, ASTM tensile bar (Daiki)	585MPasourceOutokumpu typical
Elongation at break	2.3%sourceone test result, as cast, ASTM tensile bar (Daiki)	35%sourceOutokumpu typical, A5
Young's modulus (stiffness)	79.8GPasourcestandard value (S.S.Aluminum)	200GPasourceat RT (Table 12)
Density	2,680kg/m³sourcemeasured (Daiki)	7,900kg/m³sourceat RT
Strength to weight	55.6kN·m/kg1.6x higher	34.8kN·m/kg
Stiffness to weight	29.8MN·m/kg18% higher	25.3MN·m/kg
Poisson's ratio	not sourced	0.3sourcedesign value (structural stainless steels)
Shear modulus	not sourced	76.9GPa
Bulk modulus	not sourced	167GPa
Speed of sound	5,457m/s	5,032m/s
Thermal
Thermal conductivity	125W/m·Ksourcemeasured on specimens cut from a 50 x 100 x 5 mm flat die casting (Daiki)	15W/m·Ksourceat RT
Thermal expansion	21µm/m·Ksourcemeasured, temperature range not stated (Daiki)	16µm/m·Ksourcemean, 20–100 °C
100 mm part over a 50 °C swing	105µm growth	80µm growth31% less
Specific heat	911J/kg·Ksourcemeasured (Daiki)	500J/kg·Ksourceat RT
Heats up and cools (diffusivity)	51.2mm²/s13.5x faster	3.8mm²/s
Thermal shock resistance	not sourced	902W/m
Melting point	515–582°Csourcesolidus-liquidus (Daiki)	not sourced
Max service temperature	not sourced	871°Csourcecontinuous, scaling limit
Values for	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.	1.4305 / UNS S30300, Outokumpu typical values (hot rolled, solution annealed) from 'Steel Grades, Properties and Global Standards'; max service from Carpenter CarTech 303 datasheet

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 Stainless Steel 303?

Stainless Steel 303 is stronger: its yield strength is 275 MPa against 149 MPa for Aluminum ADC12 (1.85x).

Which is lighter, Aluminum ADC12 or Stainless Steel 303?

Aluminum ADC12 is lighter: 2,680 kg/m³ against 7,900 kg/m³ for Stainless Steel 303.

Which is stiffer, Aluminum ADC12 or Stainless Steel 303?

Stainless Steel 303 is stiffer: Young's modulus 200 GPa against 79.8 GPa for Aluminum ADC12, so the same part in Stainless Steel 303 deflects less under the same load.

Which is lighter for the same job, Aluminum ADC12 or Stainless Steel 303?

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	Stainless Steel 303
Stiff rod or tie (tension)	lighter	18% heavier
Stiff beam (bending)	lighter	1.86x heavier
Stiff panel or plate	lighter	2.17x heavier
Strong rod or tie	lighter	1.6x heavier
Strong beam	lighter	1.96x heavier
Strong panel or plate	lighter	2.17x 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 Stainless Steel 303?

Aluminum ADC12 conducts heat better: 125 W/m·K against 15 W/m·K for Stainless Steel 303.

Which expands less with temperature?

Stainless Steel 303 expands less: 16 µm/m·K against 21 µm/m·K for Aluminum ADC12.

Among 72 materials

Stiffness against density

Strength against density