Materials / Compare
Steel AISI 4340 vs. Titanium
Compare Steel AISI 4340 vs. Titanium 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 | 1,035MPasourcetypical, transverse | 885MPasourcetypical, plate (>0.187 in), annealed, 0.2% offset |
| Ultimate tensile strength | 1,140MPasourcetypical, transverse | 940MPasourcetypical, plate, annealed |
| Elongation at break | 18%sourcetypical, transverse | 16%sourcetypical, in 2 in., plate annealed |
| Young's modulus (stiffness) | 200GPasourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered) | 107–122GPasourcetypical range, 20 °C |
| Density | 7,840kg/m³sourcetypical | 4,430kg/m³sourcenominal |
| Strength to weight | 132kN·m/kg | 200kN·m/kg1.51x higher |
| Stiffness to weight | 25.5MN·m/kg | 25.8MN·m/kg1% higher |
| Poisson's ratio | 0.32sourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered) | 0.342sourcemean of TIMET measurements |
| Shear modulus | 75.7GPa1.77x stiffer in shear | 42.7GPa |
| Bulk modulus | 185GPa | 121GPa |
| Speed of sound | 5,049m/s | 5,084m/s |
| Thermal | ||
| Thermal conductivity | 37.5W/m·Ksourcetypical | 6.6W/m·Ksourcetypical, 20 °C, mill annealed |
| Thermal expansion | 11.3µm/m·Ksourcemean, -18 to 93 °C | 9µm/m·Ksourcetypical, mean 0-100 °C |
| 100 mm part over a 50 °C swing | 56.5µm growth | 45µm growth26% less |
| Specific heat | 448J/kg·Ksourcetypical | 580J/kg·Ksourcetypical, 20 °C |
| Heats up and cools (diffusivity) | 10.7mm²/s4.15x faster | 2.57mm²/s |
| Thermal shock resistance | 11,678W/m3.13x more resistant | 3,730W/m |
| Melting point | not sourced | 1,630–1,650°Csourcemelting range |
| Max service temperature | not sourced | 400°Csourceupper recommended use temperature |
| Values for | Carpenter (Latrobe) Lescalloy 4340 VAC-ARC datasheet; mechanical row for 1100 °F temper; physical properties grade-level | TIMETAL 6-4 (Ti-6Al-4V Grade 5) annealed plate typical (TIMET properties manual) + TIMET datasheet TMC-0150 physical properties |
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 Steel AISI 4340 stronger than Titanium?
Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against 885 MPa for Titanium (17%).
Which is lighter, Steel AISI 4340 or Titanium?
Titanium is lighter: 4,430 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.
Which is stiffer, Steel AISI 4340 or Titanium?
Steel AISI 4340 is stiffer: Young's modulus 200 GPa against 115 GPa for Titanium, so the same part in Steel AISI 4340 deflects less under the same load.
Which is lighter for the same job, Steel AISI 4340 or Titanium?
For the same stiffness or strength: Titanium is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Steel AISI 4340 | Titanium |
|---|---|---|
| Stiff rod or tie (tension) | 1% heavier | lighter |
| Stiff beam (bending) | 34% heavier | lighter |
| Stiff panel or plate | 47% heavier | lighter |
| Strong rod or tie | 1.51x heavier | lighter |
| Strong beam | 1.59x heavier | lighter |
| Strong panel or plate | 1.64x 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, Steel AISI 4340 or Titanium?
Steel AISI 4340 conducts heat better: 37.5 W/m·K against 6.6 W/m·K for Titanium.
Which expands less with temperature?
Titanium expands less: 9 µm/m·K against 11.3 µm/m·K for Steel AISI 4340.