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FDM Polycarbonate vs. Steel AISI 4340

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

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FDM Polycarbonate3D printed (FDM)
Steel AISI 4340Wrought
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Mechanical
Yield strength53.3MPasourcetypical1,035MPasourcetypical, transverse
Ultimate tensile strength53.3MPasourcetypical, peak stress (= stress at yield)1,140MPasourcetypical, transverse
Flexural strength89.4MPasourcetypicalnot sourced
Elongation at break9.2%sourcetypical18%sourcetypical, transverse
Young's modulus (stiffness)2.39GPasourcetypical200GPasourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered)
Density1,180–1,200kg/m³sourcerange7,840kg/m³sourcetypical
Strength to weight44.8kN·m/kg132kN·m/kg2.95x higher
Stiffness to weight2.01MN·m/kg25.5MN·m/kg12.7x higher
Poisson's ratio0.38sourcebase material: polycarbonate family typical (Covestro Part and Mold Design guide, Table 3-1)0.32sourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered)
Shear modulus0.867GPa75.7GPa87.3x stiffer in shear
Bulk modulus3.33GPa185GPa
Speed of sound1,418m/s5,049m/s
Thermal
Thermal conductivity0.2W/m·Ksourcebase material: Covestro Makrolon 2405 injection-molding PC, typical, through-plane, 23 °C37.5W/m·Ksourcetypical
Thermal expansion65µm/m·Ksourcebase material: Covestro Makrolon 2405 injection-molding PC, typical, 23-55 °C, parallel11.3µm/m·Ksourcemean, -18 to 93 °C
100 mm part over a 50 °C swing325µm growth56.5µm growth5.75x less
Specific heatnot sourced448J/kg·Ksourcetypical
Heats up and cools (diffusivity)not sourced10.7mm²/s
Thermal shock resistance42.5W/m11,678W/m275x more resistant
Glass transition108°Csourcetypicalnot sourced
Max service temperature105°CsourceHDT 0.455 MPa (printed specimens)not sourced
Values forUltimaker PC, 3D-printed specimens, XY (flat); Ultimaker S5 Pro, engineering intent profile, 0.15 mm layer height, AA 0.4 print core, 100% infill, Cura 4.9, printed one-at-a-time, conditioned >=24 h at room temperature. TDS (file v5.00), April 20, 2022.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.

FDM Polycarbonate is 3D printed: its properties depend on build direction and print settings; these are typical values.

Questions

Is FDM Polycarbonate stronger than Steel AISI 4340?

Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against 53.3 MPa for FDM Polycarbonate (19.4x).

Which is lighter, FDM Polycarbonate or Steel AISI 4340?

FDM Polycarbonate is lighter: 1,190 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.

Which is stiffer, FDM Polycarbonate or Steel AISI 4340?

Steel AISI 4340 is stiffer: Young's modulus 200 GPa against 2.39 GPa for FDM Polycarbonate, so the same part in Steel AISI 4340 deflects less under the same load.

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

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

Part that must beFDM PolycarbonateSteel AISI 4340
Stiff rod or tie (tension)12.7x heavierlighter
Stiff beam (bending)39% heavierlighter
Stiff panel or platelighter1.51x heavier
Strong rod or tie2.95x heavierlighter
Strong beam10% heavierlighter
Strong panel or platelighter50% 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, FDM Polycarbonate or Steel AISI 4340?

Steel AISI 4340 conducts heat better: 37.5 W/m·K against 0.2 W/m·K for FDM Polycarbonate.

Which expands less with temperature?

Steel AISI 4340 expands less: 11.3 µm/m·K against 65 µm/m·K for FDM Polycarbonate.

Among 59 materials

1k10k0.1110100Density (kg/m³)Young's modulus (GPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonAluminumSteelIronTitaniumSteel AISI 1018Stainless 304Stainless 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel A992Stainless 303Stainless 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 PAHT-CFFDM HIPSSLA Resin Tough 2000SLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelFDM PolycarbonateSteel AISI 4340
Stiffness against density
1k10k101001kDensity (kg/m³)Yield strength (MPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonRubberAluminumSteelIronTitaniumSteel AISI 1018Stainless 304Stainless 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel A992Stainless 303Stainless 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 PAHT-CFFDM HIPSSLA Resin Tough 2000SLA Resin Elastic 50ASLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelBrickFDM PolycarbonateSteel AISI 4340
Strength against density

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