Aluminum 7050-T7451 vs. Plastic PETG

Compare Aluminum 7050-T7451 vs. Plastic PETG strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	469MPasourcetypical, longitudinal, 0.2% offset	46.2MPasourcetypical
Ultimate tensile strength	524MPasourcetypical, longitudinal	46.2MPasourcetypical, peak stress (= stress at yield)
Flexural strength	not sourced	78.9MPasourcetypical
Elongation at break	11%sourcetypical, longitudinal	7.6%sourcetypical
Young's modulus (stiffness)	70.3GPasourcetypical36.3x stiffer	1.94GPasourcetypical
Density	2,830kg/m³sourcenominal	1,270kg/m³sourcetypical
Strength to weight	166kN·m/kg4.56x higher	36.4kN·m/kg
Stiffness to weight	24.8MN·m/kg16.3x higher	1.53MN·m/kg
Poisson's ratio	0.33sourcetypical (handbook physical constant)	not sourced
Shear modulus	26.4GPa	not sourced
Bulk modulus	68.9GPa	not sourced
Speed of sound	4,984m/s	1,236m/s
Thermal
Thermal conductivity	157W/m·Ksourcetypical, 20 °C	0.21W/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical
Thermal expansion	23.5µm/m·Ksourcetypical, mean 20-100 °C	51µm/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical
100 mm part over a 50 °C swing	118µm growth2.17x less	255µm growth
Specific heat	860J/kg·Ksourcetypical, at 100 °C	1,300J/kg·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), DSC at 60 °C (lowest temperature listed)
Heats up and cools (diffusivity)	64.5mm²/s507x faster	0.127mm²/s
Thermal shock resistance	29,862W/m	not sourced
Melting point	524–635°Csourcemelting range	not sourced
Glass transition	not sourced	77.4°Csourcetypical
Max service temperature	not sourced	76.2°CsourceHDT 0.455 MPa (printed specimens)
Values for	7050-T7451 plate, Kaiser Aluminum sheet, coil & plate typical datasheet (longitudinal); Poisson from MIL-HDBK-5J	Ultimaker PETG, 3D-printed specimens, XY (flat); Ultimaker S5 Pro, engineering intent profile, 0.15 mm layer height, AA 0.4 print core, 100% infill, Cura 4.9, printed one-at-a-time, conditioned >=24 h at room temperature. TDS v1.00, April 29, 2022.

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.

Plastic PETG is 3D printed: its properties depend on build direction and print settings; these are typical values.

Questions

Is Aluminum 7050-T7451 stronger than Plastic PETG?

Aluminum 7050-T7451 is stronger: its yield strength is 469 MPa against 46.2 MPa for Plastic PETG (10.2x).

Which is lighter, Aluminum 7050-T7451 or Plastic PETG?

Plastic PETG is lighter: 1,270 kg/m³ against 2,830 kg/m³ for Aluminum 7050-T7451.

Which is stiffer, Aluminum 7050-T7451 or Plastic PETG?

Aluminum 7050-T7451 is stiffer: Young's modulus 70.3 GPa against 1.94 GPa for Plastic PETG, so the same part in Aluminum 7050-T7451 deflects less under the same load.

Which is lighter for the same job, Aluminum 7050-T7451 or Plastic PETG?

For the same stiffness or strength: Aluminum 7050-T7451 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 7050-T7451	Plastic PETG
Stiff rod or tie (tension)	lighter	16.3x heavier
Stiff beam (bending)	lighter	2.7x heavier
Stiff panel or plate	lighter	49% heavier
Strong rod or tie	lighter	4.56x heavier
Strong beam	lighter	2.1x heavier
Strong panel or plate	lighter	43% 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 7050-T7451 or Plastic PETG?

Aluminum 7050-T7451 conducts heat better: 157 W/m·K against 0.21 W/m·K for Plastic PETG.

Which expands less with temperature?

Aluminum 7050-T7451 expands less: 23.5 µm/m·K against 51 µm/m·K for Plastic PETG.

Among 72 materials

Stiffness against density

Strength against density