Nickel Inconel 718 vs. Plastic Polypropylene

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

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Plastic PolypropyleneBulk polymer (molded or machined)

Mechanical
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Yield strength	1,207MPasourcetypical, 1.0 in. hot-rolled bar, 0.2% offset	33MPasourcetypical, tensile stress at yield ISO 527
Ultimate tensile strength	1,389MPasourcetypical, 1.0 in. bar	not sourced
Elongation at break	20%sourcetypical, 1.0 in. bar	not sourced
Young's modulus (stiffness)	200GPasourcetypical, 21 °C, annealed + aged	1.45GPasourcetypical, tensile modulus ISO 527
Density	8,221kg/m³sourcenominal, annealed and aged	900kg/m³sourcetypical, 23 °C ISO 1183-1
Strength to weight	147kN·m/kg4x higher	36.7kN·m/kg
Stiffness to weight	24.3MN·m/kg15.1x higher	1.61MN·m/kg
Poisson's ratio	0.294sourcetypical, 21 °C, annealed + aged	0.42sourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
Shear modulus	77.3GPa151x stiffer in shear	0.511GPa
Bulk modulus	162GPa	3.02GPa
Speed of sound	4,932m/s	1,269m/s
Thermal
Thermal conductivity	11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a)	0.17–0.22W/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
Thermal expansion	13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged	80–100µm/m·Ksourcebase material: polypropylene homopolymer family (INEOS Olefins & Polymers USA, Typical Engineering Properties of Polypropylene)
100 mm part over a 50 °C swing	66µm growth6.82x less	450µm growth
Specific heat	435J/kg·Ksourcetypical, 21 °C	not sourced
Heats up and cools (diffusivity)	3.19mm²/s	not sourced
Thermal shock resistance	3,680W/m129x more resistant	28.6W/m
Melting point	1,260–1,336°Csourcemelting range	not sourced
Max service temperature	704°Csourceupper use temperature stated by producer	90°CsourceHDT 0.45 MPa (ISO 75B), unannealed
Values for	INCONEL 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 values	LyondellBasell Moplen HP501H polypropylene homopolymer (general purpose), typical ISO values

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 Nickel Inconel 718 stronger than Plastic Polypropylene?

Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 33 MPa for Plastic Polypropylene (36.6x).

Which is lighter, Nickel Inconel 718 or Plastic Polypropylene?

Plastic Polypropylene is lighter: 900 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.

Which is stiffer, Nickel Inconel 718 or Plastic Polypropylene?

Nickel Inconel 718 is stiffer: Young's modulus 200 GPa against 1.45 GPa for Plastic Polypropylene, 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 Polypropylene?

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 Polypropylene is lighter for a stiff panel or plate, strong panel or plate.

Part that must be	Nickel Inconel 718	Plastic Polypropylene
Stiff rod or tie (tension)	lighter	15.1x heavier
Stiff beam (bending)	lighter	29% heavier
Stiff panel or plate	1.77x heavier	lighter
Strong rod or tie	lighter	4x heavier
Strong beam	lighter	21% heavier
Strong panel or plate	1.51x heavier	lighter

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 Polypropylene?

Nickel Inconel 718 conducts heat better: 11.4 W/m·K against 0.195 W/m·K for Plastic Polypropylene.

Which expands less with temperature?

Nickel Inconel 718 expands less: 13.2 µm/m·K against 90 µm/m·K for Plastic Polypropylene.

Among 59 materials

Stiffness against density

Strength against density