Materials / Compare
Iron vs. Steel
Compare Iron vs. Steel strength, stiffness, weight and thermal properties.
| Try it on a partA bracket to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | 186MPasourcetypical (0.2% YS), hot rolled + SRA/recrystallization anneal | 385MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey), as reported by AISC |
| Ultimate tensile strength | 290MPasourcetypical, SRA/recrystallization anneal | 505MPasourcetypical: mean of 20,295 A992 flange mill-test coupons (1998 SSPC survey) |
| Elongation at break | 38%sourcetypical, gauge 4D0 | not sourced |
| Young's modulus (stiffness) | 207GPasourcetypical, after SRA/recrystallization anneal | 200GPasourcedesign value (AISC 360-16) |
| Density | 7,860kg/m³sourcetypical | 7,850kg/m³sourcenominal (constructional data) |
| Strength to weight | 23.7kN·m/kg | 49kN·m/kg2.07x higher |
| Stiffness to weight | 26.3MN·m/kg3% higher | 25.5MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | 0.3sourcedesign value (AISC 360-16 Commentary) |
| Shear modulus | 80.7GPa5% stiffer in shear | 76.9GPa |
| Bulk modulus | 158GPa | 167GPa |
| Speed of sound | 5,132m/s | 5,048m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 48W/m·Ksourcenominal at 20 °C |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 12µm/m·Ksourcenominal (constructional data, no temperature range stated) |
| 100 mm part over a 50 °C swing | 68.5µm growth | 60µm growth14% less |
| Specific heat | 450J/kg·Ksourcetypical | 460–480J/kg·Ksourcebase material: EN S275JR unalloyed structural steel (the EN counterpart of A36), typical, 50/100 °C |
| Heats up and cools (diffusivity) | 20.7mm²/s1.59x faster | 13mm²/s |
| Thermal shock resistance | 3,447W/m | 5,390W/m1.56x more resistant |
| Melting point | 1,532°Csourcetypical | not sourced |
| Values for | 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. | Generic structural steel, cited as ASTM A992 (the current US structural grade): ASTM A992 W-shapes; Fy/Fu specified minimums from AISC publications (AISC 360-16 Commentary; Modern Steel Construction); elastic constants AISC 360; physical constants from the bauforumstahl structural-steel EPD, which names A992 among covered product standards. |
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 Steel?
Steel is stronger: its yield strength is 385 MPa against 186 MPa for Iron (2.07x).
Which is lighter, Iron or Steel?
Steel is lighter: 7,850 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Iron or Steel?
Iron is stiffer: Young's modulus 207 GPa against 200 GPa for Steel, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Steel?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Steel is lighter for a strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | Steel |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 3% heavier |
| Stiff beam (bending) | lighter | 2% heavier |
| Stiff panel or plate | lighter | 1% heavier |
| Strong rod or tie | 2.07x heavier | lighter |
| Strong beam | 1.63x heavier | lighter |
| Strong panel or plate | 44% 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 conducts heat better, Iron or Steel?
Iron conducts heat better: 73.2 W/m·K against 48 W/m·K for Steel.
Which expands less with temperature?
Steel expands less: 12 µm/m·K against 13.7 µm/m·K for Iron.