Materials / Compare
Iron vs. Stainless 303
Compare Iron vs. Stainless 303 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 | 275MPasourceOutokumpu typical (product P = hot rolled plate, transverse) |
| Ultimate tensile strength | 290MPasourcetypical, SRA/recrystallization anneal | 585MPasourceOutokumpu typical |
| Elongation at break | 38%sourcetypical, gauge 4D0 | 35%sourceOutokumpu typical, A5 |
| Young's modulus (stiffness) | 207GPasourcetypical, after SRA/recrystallization anneal | 200GPasourceat RT (Table 12) |
| Density | 7,860kg/m³sourcetypical | 7,900kg/m³sourceat RT |
| Strength to weight | 23.7kN·m/kg | 34.8kN·m/kg47% higher |
| Stiffness to weight | 26.3MN·m/kg4% higher | 25.3MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | 0.3sourcedesign value (structural stainless steels) |
| Shear modulus | 80.7GPa5% stiffer in shear | 76.9GPa |
| Bulk modulus | 158GPa | 167GPa |
| Speed of sound | 5,132m/s | 5,032m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 15W/m·Ksourceat RT |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 16µm/m·Ksourcemean, 20–100 °C |
| 100 mm part over a 50 °C swing | 68.5µm growth17% less | 80µm growth |
| Specific heat | 450J/kg·Ksourcetypical | 500J/kg·Ksourceat RT |
| Heats up and cools (diffusivity) | 20.7mm²/s5.45x faster | 3.8mm²/s |
| Thermal shock resistance | 3,447W/m3.82x more resistant | 902W/m |
| Melting point | 1,532°Csourcetypical | not sourced |
| Max service temperature | not sourced | 871°Csourcecontinuous, scaling limit |
| 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. | 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 |
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 Stainless 303?
Stainless 303 is stronger: its yield strength is 275 MPa against 186 MPa for Iron (48%).
Which is lighter, Iron or Stainless 303?
Iron is lighter: 7,860 kg/m³ against 7,900 kg/m³ for Stainless 303.
Which is stiffer, Iron or Stainless 303?
Iron is stiffer: Young's modulus 207 GPa against 200 GPa for Stainless 303, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Stainless 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 303 is lighter for a strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | Stainless 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).
Which conducts heat better, Iron or Stainless 303?
Iron conducts heat better: 73.2 W/m·K against 15 W/m·K for Stainless 303.
Which expands less with temperature?
Iron expands less: 13.7 µm/m·K against 16 µm/m·K for Stainless 303.