Titanium Grade 1-4 is pure Titanium, the other grades are alloys. Pure Titanium is used due to its high corrosion resistance, the alloys because of the extremely high strength to weight ratio. Grade 1. Pure Titanium, relatively low strength and high ductility. Grade 2. The pure titanium most used. The best combination of strength, ductility and weldability. Grade 3. High strength Titanium, used for Matrix-plates in shell and tube heat exchangers. Grade 5. The most manufactured titanium alloy. Exceedingly high strength. High heat resistance. Grade 7. Superior corrosion resistance in reducing and oxidizing environments. Grade 9. Very high strength and corrosion resistance.. Grade 12. Better heat resistance than pure Titanium. Applications as for Grade 7 and Grade 11. Grade 23. Titanium-6Aluminum-4Vanadium ELI (Extra Low Interstitial) Alloy for surgical implant Applications.