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, Outokumpu, National Institute of Standards and Technology, Steel Construction Institute, Carpenter Technology
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.
Stainless Steel 303
1.4305 / UNS S30300, Outokumpu typical values (hot rolled, solution annealed) from 'Steel Grades, Properties and Global Standards'; max service from Carpenter CarTech 303 datasheet
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
2
Steel Grades, Properties and Global StandardsOutokumpuarchived copyStainless Steel 303 · Yield strength: Outokumpu typical (product P = hot rolled plate, transverse)Stainless Steel 303 · Ultimate tensile strength: Outokumpu typicalStainless Steel 303 · Elongation at break: Outokumpu typical, A5Stainless Steel 303 · Young's modulus (stiffness): at RT (Table 12)Stainless Steel 303 · Density: at RTStainless Steel 303 · Thermal conductivity: at RTStainless Steel 303 · Thermal expansion: mean, 20–100 °CStainless Steel 303 · Specific heat: at RT
3
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)
4
Design Manual for Structural Stainless Steel, 4th Edition (P413)Steel Construction Institutearchived copyStainless Steel 303 · Poisson's ratio: design value (structural stainless steels)
5
Carpenter Stainless Type 303 Data SheetCarpenter Technologyarchived copyStainless Steel 303 · Max service temperature: continuous, scaling limit
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 Stainless Steel 303?
Stainless Steel 303 is stronger: its yield strength is 275 MPa against 186 MPa for Iron (48%).
Which is lighter, Iron or Stainless Steel 303?
Iron is lighter: 7,860 kg/m³ against 7,900 kg/m³ for Stainless Steel 303.
Which is stiffer, Iron or Stainless Steel 303?
Iron is stiffer: Young's modulus 207 GPa against 200 GPa for Stainless Steel 303, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Stainless Steel 303?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Stainless Steel 303 is lighter for a strong rod or tie, strong beam, strong panel or plate.
Part that must be
Iron
Stainless Steel 303
Stiff rod or tie (tension)
lighter
4% heavier
Stiff beam (bending)
lighter
2% heavier
Stiff panel or plate
lighter
2% heavier
Strong rod or tie
47% heavier
lighter
Strong beam
29% heavier
lighter
Strong panel or plate
21% 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).
Thermal
Which conducts heat better, Iron or Stainless Steel 303?
Iron conducts heat better: 73.2 W/m·K against 15 W/m·K for Stainless Steel 303.
Which expands less with temperature?
Iron expands less: 13.7 µm/m·K against 16 µm/m·K for Stainless Steel 303.