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Aluminum A380 vs. Steel AISI 4340

Compare Aluminum A380 vs. Steel AISI 4340 strength, stiffness, weight and thermal properties.

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Aluminum A380Cast
Steel AISI 4340Wrought
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Mechanical
Yield strength160MPasourcetypical, 25 °C1,035MPasourcetypical, transverse
Ultimate tensile strength320MPasourcetypical, 25 °C1,140MPasourcetypical, transverse
Elongation at break3.5%sourcetypical18%sourcetypical, transverse
Young's modulus (stiffness)71GPasourcetypical, 25 °C200GPasourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered)
Density2,713kg/m³sourcetypical at 68 °F7,840kg/m³sourcetypical
Strength to weight59kN·m/kg132kN·m/kg2.24x higher
Stiffness to weight26.2MN·m/kg3% higher25.5MN·m/kg
Poisson's rationot sourced0.32sourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered)
Shear modulusnot sourced75.7GPa
Bulk modulusnot sourced185GPa
Speed of sound5,116m/s5,049m/s
Thermal
Thermal conductivity96.2W/m·Ksourcetypical at 68 °F37.5W/m·Ksourcetypical
Thermal expansion21.8µm/m·Ksourcetypical, 68-572 °F (20-300 °C)11.3µm/m·Ksourcemean, -18 to 93 °C
100 mm part over a 50 °C swing109µm growth56.5µm growth1.93x less
Specific heat963J/kg·Ksourcetypical at 68 °F448J/kg·Ksourcetypical
Heats up and cools (diffusivity)36.8mm²/s3.45x faster10.7mm²/s
Thermal shock resistancenot sourced11,678W/m
Values forA380 aluminium high-pressure die-casting alloy, typical properties; Rheocast Company (aluminium die caster, Germantown WI) A380 alloy data page.Carpenter (Latrobe) Lescalloy 4340 VAC-ARC datasheet; mechanical row for 1100 °F temper; physical properties grade-level

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 Aluminum A380 stronger than Steel AISI 4340?

Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against 160 MPa for Aluminum A380 (6.47x).

Which is lighter, Aluminum A380 or Steel AISI 4340?

Aluminum A380 is lighter: 2,713 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.

Which is stiffer, Aluminum A380 or Steel AISI 4340?

Steel AISI 4340 is stiffer: Young's modulus 200 GPa against 71 GPa for Aluminum A380, so the same part in Steel AISI 4340 deflects less under the same load.

Which is lighter for the same job, Aluminum A380 or Steel AISI 4340?

For the same stiffness or strength: Aluminum A380 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong panel or plate; Steel AISI 4340 is lighter for a strong rod or tie, strong beam.

Part that must beAluminum A380Steel AISI 4340
Stiff rod or tie (tension)lighter3% heavier
Stiff beam (bending)lighter1.72x heavier
Stiff panel or platelighter2.05x heavier
Strong rod or tie2.24x heavierlighter
Strong beam20% heavierlighter
Strong panel or platelighter14% 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, Aluminum A380 or Steel AISI 4340?

Aluminum A380 conducts heat better: 96.2 W/m·K against 37.5 W/m·K for Steel AISI 4340.

Which expands less with temperature?

Steel AISI 4340 expands less: 11.3 µm/m·K against 21.8 µm/m·K for Aluminum A380.

Among 72 materials

1k10k0.1110100Density (kg/m³)Young's modulus (GPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel A992Stainless Steel 303Stainless Steel 17-4PHAluminum 2024-T351Aluminum 5052-H32Aluminum 7050-T7451Titanium Ti-6Al-4VBrass C260Nickel Inconel 718Magnesium 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 SteelPCB Laminate FR-4SiliconCeramic Alumina 96%Ceramic Aluminum NitrideAluminum 6063-T6Aluminum 1100-OAluminum ADC12Magnesium AZ91DSolder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Aluminum A380Steel AISI 4340
Stiffness against density
1k10k101001kDensity (kg/m³)Yield strength (MPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonRubberAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel A992Stainless Steel 303Stainless Steel 17-4PHAluminum 2024-T351Aluminum 5052-H32Aluminum 7050-T7451Titanium Ti-6Al-4VBrass C260Nickel Inconel 718Magnesium 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 SteelBrickPCB Laminate FR-4SiliconCeramic Alumina 96%Aluminum 6063-T6Aluminum 1100-OAluminum ADC12Magnesium AZ91DSolder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Aluminum A380Steel AISI 4340
Strength against density

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