How to Choose a Titanium Grade
Start by asking what matters most for your part: strength, corrosion resistance, biocompatibility, or cost. Each titanium grade trades off these properties differently.
Need corrosion resistance without high strength? Use Grade 2. It is the most common commercially pure grade. It handles seawater, chemicals, and chlorides well. It costs less than alloy grades and is easier to machine.
Need high strength for aerospace? Use Grade 5 (Ti-6Al-4V). It is the industry standard. About half of all titanium sold worldwide is Grade 5. It works well up to 750 degrees F and has a strong fatigue life.
Need a medical implant? Use Grade 23 (Ti-6Al-4V ELI). The Extra Low Interstitial composition gives better fracture toughness and biocompatibility. It meets ASTM F136 for surgical implants.
Need lightweight tubing? Use Grade 9 (Ti-3Al-2.5V). It has half the strength of Grade 5 but is much easier to cold work into tubes. Common in hydraulic lines and bicycle frames.
Need extreme strength? Use Ti-5553. This beta alloy reaches 175 ksi tensile. It is the hardest to machine but the strongest option for landing gear and structural forgings.
Machining Titanium: Key Tips
Titanium cuts differently than steel or aluminum. It has low thermal conductivity, which means heat stays in the cutting zone. This wears tools fast and can cause work hardening. Follow these rules:
- Use sharp tools. Dull edges cause heat and chatter. Replace inserts often.
- Keep speeds low. Run at about 30-60% of the speed you use for steel.
- Use high feed rates. Stay in the cut. Do not let the tool rub.
- Flood with coolant. High-pressure coolant helps clear chips and reduce heat.
- Use rigid setups. Titanium is springy. Minimize tool overhang and use short tools.
- Climb mill when possible. Climb milling reduces tool rub and gives a better finish.