Thermal conductivity against densityHigher and further left: spreads more heat for its weightThermal expansion against thermal conductivityLower and further right: warps less when heated
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Sources5 documents: Cleveland-Cliffs, Niagara LaSalle, U.S. Department of Defense, National Institute of Standards and Technology, Ovako
Iron
Cleveland-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.
Steel AISI 1018
AISI 1018 cold drawn bar (Niagara LaSalle, cold-finished bar producer)
1
ARMCO Pure Iron Product Data Bulletin (2022)Cleveland-Cliffsarchived copyIron · Yield strength: typical (0.2% YS), hot rolled + SRA/recrystallization annealIron · Ultimate tensile strength: typical, SRA/recrystallization annealIron · Elongation at break: typical, gauge 4D0Iron · Young's modulus (stiffness): typical, after SRA/recrystallization annealIron · Density: typicalIron · Thermal conductivity: typical at 20 °CIron · Thermal expansion: mean, 20-399 °CIron · Specific heat: typicalIron · Melting point: typical
MIL-HDBK-5J, Metallic Materials and Elements for Aerospace Vehicle Structures (2003)U.S. Department of DefenseSteel AISI 1018 · Young's modulus (stiffness): base material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018)Steel AISI 1018 · Density: base material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018)Steel AISI 1018 · Poisson's ratio: base material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018)Steel AISI 1018 · Thermal conductivity: base material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018)Steel AISI 1018 · Specific heat: base material: AISI 1025 plain carbon steel (MIL-HDBK-5J design value; ASTM A108 bar is the cold-finished carbon-steel bar spec that also covers 1018)
4
Elastic Properties of Metals and Alloys, I. Iron, Nickel, and Iron-Nickel Alloys, J. Phys. Chem. Ref. Data 2 (1973)National Institute of Standards and Technologyarchived copyIron · Poisson's ratio: NIST critically evaluated best value (polycrystalline iron)
5
S275JR Steel GradeOvakoSteel AISI 1018 · Thermal expansion: base material: unalloyed carbon steel, Ovako family table (S275JR, 'none alloyed structural steels', C <= 0.21%); mean 20-300 °C
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 Iron stronger than Steel AISI 1018?
Steel AISI 1018 is stronger: its yield strength is 372 MPa against 186 MPa for Iron (2x).
Which is lighter, Iron or Steel AISI 1018?
Iron is lighter: 7,860 kg/m³ against 7,861 kg/m³ for Steel AISI 1018.
Which is stiffer, Iron or Steel AISI 1018?
Iron is stiffer: Young's modulus 207 GPa against 200 GPa for Steel AISI 1018, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Steel AISI 1018?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Steel AISI 1018 is lighter for a strong rod or tie, strong beam, strong panel or plate.
Part that must be
Iron
Steel AISI 1018
Stiff rod or tie (tension)
lighter
4% heavier
Stiff beam (bending)
lighter
2% heavier
Stiff panel or plate
lighter
1% heavier
Strong rod or tie
2x heavier
lighter
Strong beam
1.59x heavier
lighter
Strong panel or plate
41% heavier
lighter
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, Iron or Steel AISI 1018?
Iron stretches further before it breaks: 38% elongation at break against 15% for Steel AISI 1018.
Thermal
Which conducts heat better, Iron or Steel AISI 1018?
Iron conducts heat better: 73.2 W/m·K against 51.9 W/m·K for Steel AISI 1018.
Which expands less with temperature?
Steel AISI 1018 expands less: 12 µm/m·K against 13.7 µm/m·K for Iron.