The term commercially pure (CP) titanium is applied to unalloyed titanium and designates several grades containing minor amounts of impurity elements, such as carbon, iron and oxygen. The amount of oxygen can be controlled at various levels to provide increased strength. The most commonly used grade is grade 2. The compositions and properties of the four grades of CP titanium are listed below.Chemical composition (wt%) and minimum mechanical properties of CP titanium.
| Gr1 | Gr2 | Gr3 | Gr4 | |
|---|---|---|---|---|
| Nitrogen, max. | 0.03 | 0.03 | 0.05 | 0.05 |
| Carbon, max. | 0.10 | 0.10 | 0.10 | 0.10 |
| Hydrogen, max. | 0.01 | 0.01 | 0.01 | 0.01 |
| Iron, max | 0.20 | 0.30 | 0.30 | 0.50 |
| Oxygen, max. | 0.18 | 0.25 | 0.35 | 0.40 |
| Titanium | bal. | bal. | bal. | bal. |
| Yield strength (MPa) | 170 | 275 | 380 | 485 |
| Ultimate strength (MPa) | 240 | 345 | 450 | 550 |
| Elongation (%) | 24 | 20 | 18 | 15 |