Materials / Compare

Iron vs. Rubber

Compare Iron vs. Rubber strength, stiffness, weight and thermal properties.

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IronWrought
RubberBulk polymer (molded or machined)
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Mechanical
Yield strength186MPasourcetypical (0.2% YS), hot rolled + SRA/recrystallization annealnot given (tensile used)
Ultimate tensile strength290MPasourcetypical, SRA/recrystallization anneal23MPasourcetypical
Elongation at break38%sourcetypical, gauge 4D0830%sourcetypical
Young's modulus (stiffness)207GPasourcetypical, after SRA/recrystallization annealnot sourced
Density7,860kg/m³sourcetypical960kg/m³sourcetypical (specific gravity)
Strength to weight23.7kN·m/kg24kN·m/kg1% higher
Stiffness to weight26.3MN·m/kgnot sourced
Poisson's ratio0.282sourceNIST critically evaluated best value (polycrystalline iron)0.5sourcegovernment (NBS J. Res. 68A, 1964): computed by NBS for peroxide-cured gum NR vulcanizate, 25 °C, infinitesimal deformation0.49 in the solver: the linear element locks as the ratio nears 0.5 (nearly incompressible).
Shear modulus80.7GPanot sourced
Bulk modulus158GPanot sourced
Speed of sound5,132m/snot sourced
Thermal
Thermal conductivity73.2W/m·Ksourcetypical at 20 °C0.151W/m·Ksourcegovernment selected value (US Army Natick Laboratories TR 66-49-PR, 1966), soft vulcanized natural rubber, 25 °C
Thermal expansion13.7µm/m·Ksourcemean, 20-399 °Cnot sourced
100 mm part over a 50 °C swing68.5µm growthnot sourced
Specific heat450J/kg·Ksourcetypical1,881J/kg·Ksourcegovernment (NBS J. Res. 68A, Table 7; values observed for unvulcanized NR by Bekkedahl and Matheson), 25 °C
Heats up and cools (diffusivity)20.7mm²/s247x faster0.0836mm²/s
Thermal shock resistance3,447W/mnot sourced
Melting point1,532°Csourcetypicalnot sourced
Max service temperaturenot sourced70°Csourcecontinuous use operating range
Values forCleveland-Cliffs / AK Steel ARMCO Pure Iron Product Data Bulletin (07/2022): Table 1 typical physical properties, Table 2 typical mechanical properties after SRA/recrystallization anneal.Weir Minerals Linatex Premium rubber (95 % natural rubber), typical physical properties, spec sheet WMD0118/202305

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 Iron stronger than Rubber?

Iron is stronger: its yield strength is 186 MPa against tensile strength 23 MPa for Rubber (8.09x).

Which is lighter, Iron or Rubber?

Rubber is lighter: 960 kg/m³ against 7,860 kg/m³ for Iron.

Which is lighter for the same job, Iron or Rubber?

For the same stiffness or strength: Rubber is lighter for a strong rod or tie, strong beam, strong panel or plate.

Part that must beIronRubber
Strong rod or tie1% heavierlighter
Strong beam2.03x heavierlighter
Strong panel or plate2.88x 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 conducts heat better, Iron or Rubber?

Iron conducts heat better: 73.2 W/m·K against 0.151 W/m·K for Rubber.

Among 59 materials

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

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