Materials / Compare

Nickel Inconel 718 vs. Steel AISI 4340

Compare Nickel Inconel 718 vs. Steel AISI 4340 strength, stiffness, weight and thermal properties.

Nickel Inconel 718Wrought
Steel AISI 4340Wrought
MechanicalNickel Inconel 718Steel AISI 4340
Yield strength1,207MPa117% stronger1,035MPa2
Ultimate tensile strength1,389MPa122% stronger1,140MPa2
Elongation at break20%118%2
Young's modulus (stiffness)200GPa1200GPa3
Density8,221kg/m³17,840kg/m³2
Strength to weight147kN·m/kg11% higher132kN·m/kg
Stiffness to weight24.3MN·m/kg25.5MN·m/kg5% higher
Poisson's ratio0.29410.323
Shear modulus77.3GPa2% stiffer in shear75.7GPa
Bulk modulus162GPa185GPa14% higher
Speed of sound4,932m/s5,049m/s2% faster
1k10k0.1110100Density (kg/m³)Young's modulus (GPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonWoodAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110Copper C10100Copper C12200GlassSteel AISI 1045Steel A992Stainless Steel 303Stainless Steel 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 StandardSLA Resin Tough 2000SLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelConcretePCB Laminate FR-4SiliconCeramic Alumina 96%Ceramic Aluminum NitrideAluminum A380Aluminum 6063-T6Aluminum 1100-OAluminum 3003-OAluminum ADC12Magnesium AZ91DSolder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Nickel Inconel 718Steel AISI 4340
Stiffness against densityHigher and further left: stiffer for its weight
1k10k101001kDensity (kg/m³)Yield strength (MPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonRubberWoodAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110Copper C10100Copper C12200GlassSteel AISI 1045Steel A992Stainless Steel 303Stainless Steel 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 StandardSLA Resin Tough 2000SLA Resin Elastic 50ASLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelBrickPCB Laminate FR-4SiliconCeramic Alumina 96%Aluminum A380Aluminum 6063-T6Aluminum 1100-OAluminum 3003-OAluminum ADC12Magnesium AZ91DSolder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Nickel Inconel 718Steel AISI 4340
Strength against densityHigher and further left: stronger for its weight
ThermalNickel Inconel 718Steel AISI 4340
Thermal conductivity11.4W/m·K137.5W/m·K23.29x more heat through a fin
Thermal expansion13.2µm/m·K1mean11.3µm/m·K217% less
100 mm part over a 50 °C swing66µm growth56.5µm growth17% less
Specific heat435J/kg·K1448J/kg·K2
Heats up and cools (diffusivity)3.19mm²/s10.7mm²/s3.35x faster
Thermal shock resistance3,680W/m11,678W/m3.17x more resistant
Melting pointmelting range1,260–1,336°C1not sourced
Max service temperature704°C1not sourced
1k10k0.1110100Density (kg/m³)Thermal conductivity (W/m·K)Plastic PLAPlastic PETGPlastic ABSPlastic NylonRubberWoodAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110Copper C10100Copper C12200GlassSteel AISI 1045Steel A992Stainless Steel 303Stainless Steel 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 HIPSSLA Resin StandardDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelConcreteBrickPCB Laminate FR-4SiliconCeramic Alumina 96%Ceramic Aluminum NitrideAluminum A380Aluminum 6063-T6Aluminum 1100-OAluminum 3003-OAluminum ADC12Magnesium AZ91DSolder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Nickel Inconel 718Steel AISI 4340
Thermal conductivity against densityHigher and further left: spreads more heat for its weight
0.111010010100Thermal conductivity (W/m·K)Thermal expansion (µm/m·K)Plastic PETGPlastic ABSPlastic NylonWoodAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110Copper C10100Copper C12200GlassSteel AISI 1045Steel A992Stainless Steel 303Stainless Steel 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 HIPSSLA Resin StandardDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelConcreteBrickPlywoodPCB Laminate FR-4SiliconCeramic Alumina 96%Ceramic Aluminum NitrideAluminum A380Aluminum 6063-T6Aluminum 1100-OAluminum 3003-OAluminum ADC12Magnesium AZ91DSolder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Nickel Inconel 718Steel AISI 4340
Thermal expansion against thermal conductivityLower and further right: warps less when heated
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Sources3 documents: Special Metals, Carpenter Technology, U.S. Department of Defense
Nickel Inconel 718
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
Steel AISI 4340
Carpenter (Latrobe) Lescalloy 4340 VAC-ARC datasheet; mechanical row for 1100 °F temper; physical properties grade-level
  1. 1
    INCONEL alloy 718 (SMC-045)Special Metalsarchived copyNickel Inconel 718 · Yield strength: typical, 1.0 in. hot-rolled bar, 0.2% offsetNickel Inconel 718 · Ultimate tensile strength: typical, 1.0 in. barNickel Inconel 718 · Elongation at break: typical, 1.0 in. barNickel Inconel 718 · Young's modulus (stiffness): typical, 21 °C, annealed + agedNickel Inconel 718 · Density: nominal, annealed and agedNickel Inconel 718 · Poisson's ratio: typical, 21 °C, annealed + agedNickel Inconel 718 · Thermal conductivity: typical, 21 °C, annealed + aged (calculated from resistivity per footnote a)Nickel Inconel 718 · Thermal expansion: typical, mean 21-93 °C, annealed + agedNickel Inconel 718 · Specific heat: typical, 21 °CNickel Inconel 718 · Melting point: melting rangeNickel Inconel 718 · Max service temperature: upper use temperature stated by producer
  2. 2
    Lescalloy 4340 VAC-ARC Data SheetCarpenter Technologyarchived copySteel AISI 4340 · Yield strength: typical, transverseSteel AISI 4340 · Ultimate tensile strength: typical, transverseSteel AISI 4340 · Elongation at break: typical, transverseSteel AISI 4340 · Density: typicalSteel AISI 4340 · Thermal conductivity: typicalSteel AISI 4340 · Thermal expansion: mean, -18 to 93 °CSteel AISI 4340 · Specific heat: typical
  3. 3
    MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures (2003)U.S. Department of DefenseSteel AISI 4340 · Young's modulus (stiffness): MIL-HDBK-5J design value (AISI 4340, quenched and tempered)Steel AISI 4340 · Poisson's ratio: MIL-HDBK-5J design value (AISI 4340, quenched and tempered)

Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

Questions

Mechanical

Is Nickel Inconel 718 stronger than Steel AISI 4340?

Nickel Inconel 718 is stronger: its yield strength is 1,207 MPa against 1,035 MPa for Steel AISI 4340 (17%).

Which is lighter, Nickel Inconel 718 or Steel AISI 4340?

Steel AISI 4340 is lighter: 7,840 kg/m³ against 8,221 kg/m³ for Nickel Inconel 718.

Which is stiffer, Nickel Inconel 718 or Steel AISI 4340?

Nickel Inconel 718 is stiffer: Young's modulus 200 GPa against 200 GPa for Steel AISI 4340, 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 Steel AISI 4340?

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 4340 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate.

Part that must beNickel Inconel 718Steel AISI 4340
Stiff rod or tie (tension)5% heavierlighter
Stiff beam (bending)5% heavierlighter
Stiff panel or plate5% heavierlighter
Strong rod or tielighter11% heavier
Strong beamlighter6% heavier
Strong panel or platelighter3% 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).

Thermal

Which conducts heat better, Nickel Inconel 718 or Steel AISI 4340?

Steel AISI 4340 conducts heat better: 37.5 W/m·K against 11.4 W/m·K for Nickel Inconel 718.

Which expands less with temperature?

Steel AISI 4340 expands less: 11.3 µm/m·K against 13.2 µm/m·K for Nickel Inconel 718.

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