Materials / Compare
Iron vs. Stainless 17-4PH
Compare Iron vs. Stainless 17-4PH 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 | 1,275MPasourcetypical, transverse, sheet/strip |
| Ultimate tensile strength | 290MPasourcetypical, SRA/recrystallization anneal | 1,379MPasourcetypical, transverse, sheet/strip |
| Elongation at break | 38%sourcetypical, gauge 4D0 | 9%sourcetypical, transverse, in 2 in. (50.8 mm) |
| Young's modulus (stiffness) | 207GPasourcetypical, after SRA/recrystallization anneal | 197GPasourceH 900 |
| Density | 7,860kg/m³sourcetypical | 7,800kg/m³sourceH 900 |
| Strength to weight | 23.7kN·m/kg | 163kN·m/kg6.91x higher |
| Stiffness to weight | 26.3MN·m/kg4% higher | 25.3MN·m/kg |
| Poisson's ratio | 0.282sourceNIST critically evaluated best value (polycrystalline iron) | 0.272sourceH 900 (column) |
| Shear modulus | 80.7GPa4% stiffer in shear | 77.4GPa |
| Bulk modulus | 158GPa | 144GPa |
| Speed of sound | 5,132m/s | 5,026m/s |
| Thermal | ||
| Thermal conductivity | 73.2W/m·Ksourcetypical at 20 °C | 17.9W/m·Ksourceat 149 °C (300 °F), H 900 |
| Thermal expansion | 13.7µm/m·Ksourcemean, 20-399 °C | 10.8µm/m·Ksourcemean, 21–93 °C (70–200 °F), H 900 |
| 100 mm part over a 50 °C swing | 68.5µm growth | 54µm growth27% less |
| Specific heat | 450J/kg·Ksourcetypical | 460J/kg·Ksourcemean, 0–100 °C, H 900 |
| Heats up and cools (diffusivity) | 20.7mm²/s4.15x faster | 4.99mm²/s |
| Thermal shock resistance | 3,447W/m | 7,809W/m2.27x more resistant |
| Melting point | 1,532°Csourcetypical | not sourced |
| Max service temperature | not sourced | 316°Csourcestrength-retention limit (not oxidation) |
| 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. | Cleveland-Cliffs 17-4 PH, Condition H 900, sheet/strip, transverse (Product Data Bulletin, May 2021) |
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 17-4PH?
Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 186 MPa for Iron (6.85x).
Which is lighter, Iron or Stainless 17-4PH?
Stainless 17-4PH is lighter: 7,800 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Iron or Stainless 17-4PH?
Iron is stiffer: Young's modulus 207 GPa against 197 GPa for Stainless 17-4PH, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Stainless 17-4PH?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending); Stainless 17-4PH is lighter for a strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Iron | Stainless 17-4PH |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 4% heavier |
| Stiff beam (bending) | lighter | 2% heavier |
| Stiff panel or plate | about equal | about equal |
| Strong rod or tie | 6.91x heavier | lighter |
| Strong beam | 3.64x heavier | lighter |
| Strong panel or plate | 2.64x 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 17-4PH?
Iron conducts heat better: 73.2 W/m·K against 17.9 W/m·K for Stainless 17-4PH.
Which expands less with temperature?
Stainless 17-4PH expands less: 10.8 µm/m·K against 13.7 µm/m·K for Iron.