Nickel Inconel 718 vs. Stainless 17-4PH

Compare Nickel Inconel 718 vs. Stainless 17-4PH 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	1,275MPasourcetypical, transverse, sheet/strip
Ultimate tensile strength	1,389MPasourcetypical, 1.0 in. bar	1,379MPasourcetypical, transverse, sheet/strip
Elongation at break	20%sourcetypical, 1.0 in. bar	9%sourcetypical, transverse, in 2 in. (50.8 mm)
Young's modulus (stiffness)	200GPasourcetypical, 21 °C, annealed + aged	197GPasourceH 900
Density	8,221kg/m³sourcenominal, annealed and aged	7,800kg/m³sourceH 900
Strength to weight	147kN·m/kg	163kN·m/kg11% higher
Stiffness to weight	24.3MN·m/kg	25.3MN·m/kg4% higher
Poisson's ratio	0.294sourcetypical, 21 °C, annealed + aged	0.272sourceH 900 (column)
Shear modulus	77.3GPa	77.4GPa
Bulk modulus	162GPa	144GPa
Speed of sound	4,932m/s	5,026m/s
Thermal
Thermal conductivity	11.4W/m·Ksourcetypical, 21 °C, annealed + aged (calculated from resistivity per footnote a)	17.9W/m·Ksourceat 149 °C (300 °F), H 900
Thermal expansion	13.2µm/m·Ksourcetypical, mean 21-93 °C, annealed + aged	10.8µm/m·Ksourcemean, 21–93 °C (70–200 °F), H 900
100 mm part over a 50 °C swing	66µm growth	54µm growth22% less
Specific heat	435J/kg·Ksourcetypical, 21 °C	460J/kg·Ksourcemean, 0–100 °C, H 900
Heats up and cools (diffusivity)	3.19mm²/s	4.99mm²/s1.56x faster
Thermal shock resistance	3,680W/m	7,809W/m2.12x more resistant
Melting point	1,260–1,336°Csourcemelting range	not sourced
Max service temperature	704°Csourceupper use temperature stated by producer	316°Csourcestrength-retention limit (not oxidation)
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	Cleveland-Cliffs 17-4 PH, Condition H 900, sheet/strip, transverse (Product Data Bulletin, May 2021)

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 Stainless 17-4PH?

Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 1,207 MPa for Nickel Inconel 718 (6%).

Which is lighter, Nickel Inconel 718 or Stainless 17-4PH?

Stainless 17-4PH is lighter: 7,800 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.

Which is stiffer, Nickel Inconel 718 or Stainless 17-4PH?

Nickel Inconel 718 is stiffer: Young's modulus 200 GPa against 197 GPa for Stainless 17-4PH, 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 Stainless 17-4PH?

For the same stiffness or strength: Stainless 17-4PH 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	Nickel Inconel 718	Stainless 17-4PH
Stiff rod or tie (tension)	4% heavier	lighter
Stiff beam (bending)	5% heavier	lighter
Stiff panel or plate	5% heavier	lighter
Strong rod or tie	11% heavier	lighter
Strong beam	9% heavier	lighter
Strong panel or plate	8% 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 Stainless 17-4PH?

Stainless 17-4PH conducts heat better: 17.9 W/m·K against 11.4 W/m·K for Nickel Inconel 718.

Which expands less with temperature?

Stainless 17-4PH expands less: 10.8 µm/m·K against 13.2 µm/m·K for Nickel Inconel 718.

Among 59 materials

Stiffness against density

Strength against density