Nickel Inconel 718 vs. Steel AISI 1045

Compare Nickel Inconel 718 vs. Steel AISI 1045 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	1,207MPasourcetypical, 1.0 in. hot-rolled bar, 0.2% offset	531MPasourceproducer-stated, cold drawn
Ultimate tensile strength	1,389MPasourcetypical, 1.0 in. bar	627MPasourceproducer-stated, cold drawn
Elongation at break	20%sourcetypical, 1.0 in. bar	12%sourcein 2 in (50.8 mm)
Young's modulus (stiffness)	200GPasourcetypical, 21 °C, annealed + aged	210GPasourcetypical
Density	8,221kg/m³sourcenominal, annealed and aged	7,800kg/m³sourcetypical
Strength to weight	147kN·m/kg2.16x higher	68.1kN·m/kg
Stiffness to weight	24.3MN·m/kg	26.9MN·m/kg11% higher
Poisson's ratio	0.294sourcetypical, 21 °C, annealed + aged	0.3sourcetypical
Shear modulus	77.3GPa	80.8GPa5% stiffer in shear
Bulk modulus	162GPa	175GPa
Speed of sound	4,932m/s	5,189m/s
Thermal
Thermal conductivity	11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a)	40–45W/m·Ksourcetypical range, ambient
Thermal expansion	13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged	12µm/m·Ksourcetypical, mean 20-300 °C
100 mm part over a 50 °C swing	66µm growth	60µm growth10% less
Specific heat	435J/kg·Ksourcetypical, 21 °C	460–480J/kg·Ksourcetypical range, 50/100 °C
Heats up and cools (diffusivity)	3.19mm²/s	11.6mm²/s3.64x faster
Thermal shock resistance	3,680W/m	6,269W/m1.7x more resistant
Melting point	1,260–1,336°Csourcemelting range	not sourced
Max service temperature	704°Csourceupper use temperature stated by producer	not sourced
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	AISI 1045 cold drawn bar (Niagara LaSalle) for mechanical; Ovako C45 (lists 'SAE 1045' as a similar designation) for physical constants

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 Steel AISI 1045?

Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 531 MPa for Steel AISI 1045 (2.27x).

Which is lighter, Nickel Inconel 718 or Steel AISI 1045?

Steel AISI 1045 is lighter: 7,800 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.

Which is stiffer, Nickel Inconel 718 or Steel AISI 1045?

Steel AISI 1045 is stiffer: Young's modulus 210 GPa against 200 GPa for Nickel Inconel 718, so the same part in Steel AISI 1045 deflects less under the same load.

Which is lighter for the same job, Nickel Inconel 718 or Steel AISI 1045?

For the same stiffness or strength: Nickel Inconel 718 is lighter for a strong rod or tie, strong beam, strong panel or plate; Steel AISI 1045 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate.

Part that must be	Nickel Inconel 718	Steel AISI 1045
Stiff rod or tie (tension)	11% heavier	lighter
Stiff beam (bending)	8% heavier	lighter
Stiff panel or plate	7% heavier	lighter
Strong rod or tie	lighter	2.16x heavier
Strong beam	lighter	1.64x 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, Nickel Inconel 718 or Steel AISI 1045?

Steel AISI 1045 conducts heat better: 42.5 W/m·K against 11.4 W/m·K for Nickel Inconel 718.

Which expands less with temperature?

Steel AISI 1045 expands less: 12 µm/m·K against 13.2 µm/m·K for Nickel Inconel 718.

Among 59 materials

Stiffness against density

Strength against density