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Nickel Inconel 718 vs. Plastic PETG

Compare Nickel Inconel 718 vs. Plastic PETG strength, stiffness, weight and thermal properties.

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Nickel Inconel 718Wrought
Plastic PETG3D printed (FDM)
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Mechanical
Yield strength1,207MPasourcetypical, 1.0 in. hot-rolled bar, 0.2% offset46.2MPasourcetypical
Ultimate tensile strength1,389MPasourcetypical, 1.0 in. bar46.2MPasourcetypical, peak stress (= stress at yield)
Flexural strengthnot sourced78.9MPasourcetypical
Elongation at break20%sourcetypical, 1.0 in. bar7.6%sourcetypical
Young's modulus (stiffness)200GPasourcetypical, 21 °C, annealed + aged1.94GPasourcetypical
Density8,221kg/m³sourcenominal, annealed and aged1,270kg/m³sourcetypical
Strength to weight147kN·m/kg4.04x higher36.4kN·m/kg
Stiffness to weight24.3MN·m/kg15.9x higher1.53MN·m/kg
Poisson's ratio0.294sourcetypical, 21 °C, annealed + agednot sourced
Shear modulus77.3GPanot sourced
Bulk modulus162GPanot sourced
Speed of sound4,932m/s1,236m/s
Thermal
Thermal conductivity11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a)0.21W/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical
Thermal expansion13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged51µm/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical
100 mm part over a 50 °C swing66µm growth3.86x less255µm growth
Specific heat435J/kg·Ksourcetypical, 21 °C1,300J/kg·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), DSC at 60 °C (lowest temperature listed)
Heats up and cools (diffusivity)3.19mm²/s25.1x faster0.127mm²/s
Thermal shock resistance3,680W/mnot sourced
Melting point1,260–1,336°Csourcemelting rangenot sourced
Glass transitionnot sourced77.4°Csourcetypical
Max service temperature704°Csourceupper use temperature stated by producer76.2°CsourceHDT 0.455 MPa (printed specimens)
Values forINCONEL alloy 718, standard grade, 1750 °F/1 hr anneal + 1325 °F/8 hr F.C. to 1150 °F aged; Special Metals bulletin SMC-045 typical valuesUltimaker 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 Nickel Inconel 718 stronger than Plastic PETG?

Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 46.2 MPa for Plastic PETG (26.1x).

Which is lighter, Nickel Inconel 718 or Plastic PETG?

Plastic PETG is lighter: 1,270 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.

Which is stiffer, Nickel Inconel 718 or Plastic PETG?

Nickel Inconel 718 is stiffer: Young's modulus 200 GPa against 1.94 GPa for Plastic PETG, so the same part in Nickel Inconel 718 deflects less under the same load.

Which is lighter for the same job, Nickel Inconel 718 or Plastic PETG?

For the same stiffness or strength: Nickel Inconel 718 is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie, strong beam; Plastic PETG is lighter for a stiff panel or plate, strong panel or plate.

Part that must beNickel Inconel 718Plastic PETG
Stiff rod or tie (tension)lighter15.9x heavier
Stiff beam (bending)lighter1.57x heavier
Stiff panel or plate38% heavierlighter
Strong rod or tielighter4.04x heavier
Strong beamlighter36% heavier
Strong panel or plate27% heavierlighter

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, Nickel Inconel 718 or Plastic PETG?

Nickel Inconel 718 conducts heat better: 11.4 W/m·K against 0.21 W/m·K for Plastic PETG.

Which expands less with temperature?

Nickel Inconel 718 expands less: 13.2 µm/m·K against 51 µm/m·K for Plastic PETG.

Among 59 materials

1k10k0.1110100Density (kg/m³)Young's modulus (GPa)Plastic PLAPlastic ABSPlastic TPUPlastic NylonAluminumSteelIronTitaniumSteel AISI 1018Stainless 304Stainless 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel AISI 4340Steel A992Stainless 303Stainless 17-4PHAluminum 2024-T351Aluminum 5052-H32Aluminum 7050-T7451Titanium Ti-6Al-4VBrass C260Magnesium AZ31B-H24Zinc Zamak 3Plastic ABS (bulk/injection)Plastic PolycarbonatePlastic POM/AcetalPlastic Nylon PA6Plastic Nylon PA66Plastic PEEKPlastic UHMWPEPlastic HDPEPlastic PolypropylenePlastic PMMAFDM ASAFDM PolycarbonateFDM PAHT-CFFDM HIPSSLA Resin Tough 2000SLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelNickel Inconel 718Plastic PETG
Stiffness against density
1k10k101001kDensity (kg/m³)Yield strength (MPa)Plastic PLAPlastic ABSPlastic TPUPlastic NylonRubberAluminumSteelIronTitaniumSteel AISI 1018Stainless 304Stainless 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel AISI 4340Steel A992Stainless 303Stainless 17-4PHAluminum 2024-T351Aluminum 5052-H32Aluminum 7050-T7451Titanium Ti-6Al-4VBrass C260Magnesium AZ31B-H24Zinc Zamak 3Plastic ABS (bulk/injection)Plastic PolycarbonatePlastic POM/AcetalPlastic Nylon PA6Plastic Nylon PA66Plastic PEEKPlastic PTFEPlastic UHMWPEPlastic HDPEPlastic PolypropylenePlastic PMMAFDM ASAFDM PolycarbonateFDM PAHT-CFFDM HIPSSLA Resin Tough 2000SLA Resin Elastic 50ASLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelBrickNickel Inconel 718Plastic PETG
Strength against density

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