Materials / Compare

Steel AISI 1045 vs. Steel AISI 4340

Compare Steel AISI 1045 vs. Steel AISI 4340 strength, stiffness, weight and thermal properties.

Steel AISI 1045Wrought
Steel AISI 4340Wrought
MechanicalSteel AISI 1045Steel AISI 4340
Yield strengthproducer-stated531MPa11,035MPa21.95x stronger
Ultimate tensile strengthproducer-stated627MPa11,140MPa21.82x stronger
Elongation at breakin 2 in12%118%21.5x more ductile
Young's modulus (stiffness)210GPa3200GPa4
Density7,800kg/m³37,840kg/m³2
Strength to weight68.1kN·m/kg132kN·m/kg1.94x higher
Stiffness to weight26.9MN·m/kg6% higher25.5MN·m/kg
Poisson's ratio0.330.324
Shear modulus80.8GPa7% stiffer in shear75.7GPa
Bulk modulus175GPa185GPa6% higher
Speed of sound5,189m/s3% faster5,049m/s
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 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 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 GF30Steel AISI 1045Steel 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 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 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 GF30Steel AISI 1045Steel AISI 4340
Strength against densityHigher and further left: stronger for its weight
ThermalSteel AISI 1045Steel AISI 4340
Thermal conductivity40–45W/m·K337.5W/m·K2
Thermal expansion12µm/m·K3mean11.3µm/m·K2
100 mm part over a 50 °C swing60µm growth56.5µm growth6% less
Specific heat460–480J/kg·K3448J/kg·K2
Heats up and cools (diffusivity)11.6mm²/s9% faster10.7mm²/s
Thermal shock resistance6,269W/m11,678W/m1.86x more resistant
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 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 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 GF30Steel AISI 1045Steel 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 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 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 GF30Steel AISI 1045Steel AISI 4340
Thermal expansion against thermal conductivityLower and further right: warps less when heated
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Sources4 documents: Niagara LaSalle, Carpenter Technology, Ovako, U.S. Department of Defense
Steel AISI 1045
AISI 1045 cold drawn bar (Niagara LaSalle) for mechanical; Ovako C45 (lists 'SAE 1045' as a similar designation) for physical constants
Steel AISI 4340
Carpenter (Latrobe) Lescalloy 4340 VAC-ARC datasheet; mechanical row for 1100 °F temper; physical properties grade-level
  1. 1
    1045 PropertiesNiagara LaSallearchived copySteel AISI 1045 · Yield strength: producer-stated, cold drawnSteel AISI 1045 · Ultimate tensile strength: producer-stated, cold drawnSteel AISI 1045 · Elongation at break: in 2 in (50.8 mm)
  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
    C45 Steel GradeOvakoSteel AISI 1045 · Young's modulus (stiffness): typicalSteel AISI 1045 · Density: typicalSteel AISI 1045 · Poisson's ratio: typicalSteel AISI 1045 · Thermal conductivity: typical range, ambientSteel AISI 1045 · Thermal expansion: typical, mean 20-300 °CSteel AISI 1045 · Specific heat: typical range, 50/100 °C
  4. 4
    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 Steel AISI 1045 stronger than Steel AISI 4340?

Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against 531 MPa for Steel AISI 1045 (1.95x).

Which is lighter, Steel AISI 1045 or Steel AISI 4340?

Steel AISI 1045 is lighter: 7,800 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.

Which is stiffer, Steel AISI 1045 or Steel AISI 4340?

Steel AISI 1045 is stiffer: Young's modulus 210 GPa against 200 GPa for Steel AISI 4340, so the same part in Steel AISI 1045 deflects less under the same load.

Which is lighter for the same job, Steel AISI 1045 or Steel AISI 4340?

For the same stiffness or strength: Steel AISI 1045 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Steel AISI 4340 is lighter for a strong rod or tie, strong beam, strong panel or plate.

Part that must beSteel AISI 1045Steel AISI 4340
Stiff rod or tie (tension)lighter6% heavier
Stiff beam (bending)lighter3% heavier
Stiff panel or platelighter2% heavier
Strong rod or tie1.94x heavierlighter
Strong beam1.55x heavierlighter
Strong panel or plate39% heavierlighter

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 is more ductile, Steel AISI 1045 or Steel AISI 4340?

Steel AISI 4340 stretches further before it breaks: 18% elongation at break against 12% for Steel AISI 1045.

Thermal

Which conducts heat better, Steel AISI 1045 or Steel AISI 4340?

Steel AISI 1045 conducts heat better: 42.5 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 12 µm/m·K for Steel AISI 1045.

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