Materials / Compare
Glass vs. Iron
Compare Glass vs. Iron 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) | 186MPasourcetypical (0.2% YS), hot rolled + SRA/recrystallization anneal |
| Ultimate tensile strength | 41MPasourcetypical mean surface tensile stress at fracture (MOR), 60 s load, weathered, 50% breakage probability | 290MPasourcetypical, SRA/recrystallization anneal |
| Flexural strength | 41MPasourcemean MOR (same value as tensile) | not sourced |
| Elongation at break | not sourced | 38%sourcetypical, gauge 4D0 |
| Young's modulus (stiffness) | 72GPasourcetypical | 207GPasourcetypical, after SRA/recrystallization anneal |
| Density | 2,500kg/m³sourcetypical3.14x lighter | 7,860kg/m³sourcetypical |
| Strength to weight | 16.4kN·m/kg | 23.7kN·m/kg44% higher |
| Stiffness to weight | 28.8MN·m/kg9% higher | 26.3MN·m/kg |
| Poisson's ratio | 0.22sourcetypical | 0.282sourceNIST critically evaluated best value (polycrystalline iron) |
| Shear modulus | 29.5GPa | 80.7GPa2.74x stiffer in shear |
| Bulk modulus | 42.9GPa | 158GPa |
| Speed of sound | 5,367m/s | 5,132m/s |
| Thermal | ||
| Thermal conductivity | 0.937W/m·Ksourcetypical at 75 F | 73.2W/m·Ksourcetypical at 20 °C |
| Thermal expansion | 8.3µm/m·Ksourcetypical, 75-575 F | 13.7µm/m·Ksourcemean, 20-399 °C |
| 100 mm part over a 50 °C swing | 41.5µm growth1.65x less | 68.5µm growth |
| Specific heat | 880J/kg·Ksourcetypical at 75 F | 450J/kg·Ksourcetypical |
| Heats up and cools (diffusivity) | 0.426mm²/s | 20.7mm²/s48.6x faster |
| Thermal shock resistance | 50.1W/m | 3,447W/m68.7x more resistant |
| Melting point | not sourced | 1,532°Csourcetypical |
| 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) | 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. |
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 Iron?
Iron is stronger: its yield strength is 186 MPa against tensile strength 41 MPa for Glass (4.54x).
Which is lighter, Glass or Iron?
Glass is lighter: 2,500 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Glass or Iron?
Iron is stiffer: Young's modulus 207 GPa against 72 GPa for Glass, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Glass or Iron?
For the same stiffness or strength: Glass is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong beam, strong panel or plate; Iron is lighter for a strong rod or tie.
| Part that must be | Glass | Iron |
|---|---|---|
| Stiff rod or tie (tension) | lighter | 9% heavier |
| Stiff beam (bending) | lighter | 1.85x heavier |
| Stiff panel or plate | lighter | 2.21x heavier |
| Strong rod or tie | 44% heavier | lighter |
| Strong beam | lighter | 15% heavier |
| Strong panel or plate | lighter | 48% heavier |
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 Iron?
Iron conducts heat better: 73.2 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 13.7 µm/m·K for Iron.