The modulus of elasticity (Young modulus) measures a material stiffness: how much it resists elastic deflection under load. This chart compares common engineering materials.
| Material | GPa | Mpsi |
|---|---|---|
| Carbon and alloy steel | 200 | 29 |
| Stainless steel | 193 | 28 |
| Cast iron (gray) | 100 to 150 | 15 to 22 |
| Titanium | 110 | 16 |
| Copper | 117 | 17 |
| Brass | 100 to 110 | 15 to 16 |
| Bronze | 100 to 120 | 15 to 17 |
| Aluminum | 69 | 10 |
| Magnesium | 45 | 6.5 |
| PEEK | 3.6 | 0.52 |
| Acetal (Delrin) | 3.1 | 0.45 |
| Polycarbonate | 2.3 | 0.33 |
| ABS | 2.3 | 0.33 |
| Nylon | 2 to 3 | 0.3 to 0.43 |
| UHMW | 0.7 | 0.10 |
| PTFE | 0.5 | 0.07 |
See the Yield Strength Chart and the Stress Calculator.
Stiffness is not strength
The modulus of elasticity tells you how much a material resists bending or stretching in the elastic range. A stiffer material deflects less under the same load. It is a different property from strength, which is how much load a material can take before it yields or breaks. A very strong material can still be quite flexible.
Using the values
Deflection of a beam is inversely proportional to the modulus, so aluminum, with about one third the modulus of steel, bends roughly three times as much for the same shape and load. Heat treating changes the strength of steel but not its stiffness. The values given are typical and change a little with temperature and alloy. One million pounds per square inch is about 6.9 gigapascals.