Titanium Alloys are generally divided into three groups (Alpha, Alpha-Beta and Beta). The Alpha group contain most importantly aluminum and tin. They can also contain molybdenum, zirconium, nitrogen, vanadium, columbium, tantalum, and silicon. Alpha alloys are not suitable for heat treatment. Alpha alloys are used for aircraft parts and cryogenic equipment.

The Alpha-Beta group can be strengthened by heat treatment. The alloys are used in aircraft and aircraft turbine parts, chemical processing equipment, marine hardware.

The Beta Alloys have good hardenability. Beta alloys are slightly more dense than other titanium alloys, having densities ranging from 4800 to 5050 kg/m3. They are the least creep resistant alloys, they are weldable, and can have yield strength up to 1345 x 106 Pa.(Solution annealing and age hardened) Beta alloys are the smallest group. They are used for heavier duty purposes on aircraft.

Titanium is a light metal having a density of about 4540 kg/m3. This compares to steel at 7900 kg/m3 and Aluminium at 2710kg/m3. Titanium has a melting point of about 1668oC which is higher than iron at1560oC. Titanium has a Modulus of Elasticity of 110 x 109 Pa. compared to steel at 210 x 109 Pa. Therefore Titanium has a significantly high deflection under the same load than steel. Pure Titanium can be cold rolled to 90% reduction in thickness at room temperatures without cracking.

There are a number of grades of commercially pure (unalloyed) titanium as identified in ASTM B265 (Gr,1,2,3,4,7,11,and 12) (see table below for Gr 1 to 4)). Each grade has a different amount of impurity content (Grade 1 have lowest impurities). Grade 1 to 4 are classified as pure even though grade 4 is much stronger and less ductile than grade 1. Grade 4 contains higher levels of oxygen which is classified ( for pure titanium ) as an alloying element. Oxygen and Nitrogen and Carbon are all interstitial alloys (they insert themselves in the crystal intertices of the crystals and prevent relative sliding). They therefore increase the hardness and reduce the ductility. Oxygen is the main element controlling the strength of unalloyed titanium.