Materials / Compare
Glass vs. Steel AISI 4340
Compare Glass vs. Steel AISI 4340 strength, stiffness, weight and thermal properties.
| Try it on a partA sample part to run stress or thermal on, free in your browser | Open in LessCAD | Open in LessCAD |
|---|---|---|
| Mechanical | ||
| Yield strength | not given (tensile used) | 1,035MPasourcetypical, transverse |
| Ultimate tensile strength | 41MPasourcetypical mean surface tensile stress at fracture (MOR), 60 s load, weathered, 50% breakage probability | 1,140MPasourcetypical, transverse |
| Flexural strength | 41MPasourcemean MOR (same value as tensile) | not sourced |
| Elongation at break | not sourced | 18%sourcetypical, transverse |
| Young's modulus (stiffness) | 72GPasourcetypical | 200GPasourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered) |
| Density | 2,500kg/m³sourcetypical3.14x lighter | 7,840kg/m³sourcetypical |
| Strength to weight | 16.4kN·m/kg | 132kN·m/kg8.05x higher |
| Stiffness to weight | 28.8MN·m/kg13% higher | 25.5MN·m/kg |
| Poisson's ratio | 0.22sourcetypical | 0.32sourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered) |
| Shear modulus | 29.5GPa | 75.7GPa2.57x stiffer in shear |
| Bulk modulus | 42.9GPa | 185GPa |
| Speed of sound | 5,367m/s | 5,049m/s |
| Thermal | ||
| Thermal conductivity | 0.937W/m·Ksourcetypical at 75 F | 37.5W/m·Ksourcetypical |
| Thermal expansion | 8.3µm/m·Ksourcetypical, 75-575 F | 11.3µm/m·Ksourcemean, -18 to 93 °C |
| 100 mm part over a 50 °C swing | 41.5µm growth36% less | 56.5µm growth |
| Specific heat | 880J/kg·Ksourcetypical at 75 F | 448J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.426mm²/s | 10.7mm²/s25.1x faster |
| Thermal shock resistance | 50.1W/m | 11,678W/m233x more resistant |
| Max service temperature | 511°Csourcestrain point (ASTM C336) - stress-relaxation onset, not a rated service limit | not sourced |
| Values for | Annealed soda-lime-silica float glass, Pilkington North America Technical Bulletin ATS-129 (04/2025) | Carpenter (Latrobe) Lescalloy 4340 VAC-ARC datasheet; mechanical row for 1100 °F temper; physical properties grade-level |
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 Glass stronger than Steel AISI 4340?
Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against tensile strength 41 MPa for Glass (25.2x).
Which is lighter, Glass or Steel AISI 4340?
Glass is lighter: 2,500 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.
Which is stiffer, Glass or Steel AISI 4340?
Steel AISI 4340 is stiffer: Young's modulus 200 GPa against 72 GPa for Glass, so the same part in Steel AISI 4340 deflects less under the same load.
Which is lighter for the same job, Glass or Steel AISI 4340?
For the same stiffness or strength: Glass is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Steel AISI 4340 is lighter for a strong rod or tie, strong beam, strong panel or plate.
| Part that must be | Glass | Steel AISI 4340 |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 13% heavier |
| Stiff beam (bending) | lighter | 1.88x heavier |
| Stiff panel or plate | lighter | 2.23x heavier |
| Strong rod or tie | 8.05x heavier | lighter |
| Strong beam | 2.74x heavier | lighter |
| Strong panel or plate | 1.6x 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, Glass or Steel AISI 4340?
Steel AISI 4340 conducts heat better: 37.5 W/m·K against 0.937 W/m·K for Glass.
Which expands less with temperature?
Glass expands less: 8.3 µm/m·K against 11.3 µm/m·K for Steel AISI 4340.