What are the main compositional differences between Grade 2 and Grade 4 titanium?
Both Grade 2 and Grade 4 are commercially pure titanium grades, not alloys. Their main difference lies in interstitial element contents, especially oxygen and iron, which directly control strength and ductility.
1. Oxygen Content
Oxygen is the most influential element for pure titanium strength.
Grade 2: max 0.20%
Grade 4: max 0.40%
Grade 4 has twice the oxygen level of Grade 2, which greatly increases tensile strength.
2. Iron Content
Iron is the most common metallic impurity and also strengthens titanium.
Grade 2: max 0.10%
Grade 4: max 0.50%
Grade 4 permits five times more iron than Grade 2.
3. Other Elements
Hydrogen: <= 0.015%
Nitrogen: <= 0.03%
Carbon: <= 0.05%
Titanium balance: both are >= 99.0%
The key compositional difference is that Grade 4 has much higher oxygen and iron contents than Grade 2.
Higher interstitial elements make Grade 4 the strongest commercially pure titanium, while Grade 2 has better ductility, formability, and toughness.
