[Aramith]

Grade 1 is the most ductile and softest titanium alloy. It is a good solution for cold forming and corrosive environments.ASTM/ ASME SB-265 provides the standards for commercially pure titanium sheet and plate.[6]
Grade 2 Unalloyed titanium, standard oxygen.
Grade 2H Unalloyed titanium (Grade 2 with 58 ksi minimum UTS).
Grade 3 Unalloyed titanium, medium oxygen.
Grades 1-4 are unalloyed and considered commercially pure or "CP". Generally the tensile and yield strength goes up with grade number for these "pure" grades. The difference in their physical properties is primarily due to the quantity of interstitial elements. They are used for corrosion resistance applications where cost, ease of fabrication, and welding are important.
Grade 5, also known as Ti6Al4V, Ti-6Al-4V or Ti 6-4, is the most commonly used alloy. It has a chemical composition of 6% aluminum, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium.[7] It is significantly stronger than commercially pure titanium while having the same stiffness and thermal properties (excluding thermal conductivity, which is about 60% lower in Grade 5 Ti than in CP Ti).[8] Among its many advantages, it is heat treatable. This grade is an excellent combination of strength, corrosion resistance, weld and fabricability.