Titanium does not occur free in Nature. However, when combined with other elements, it is quite abundant, occurring in small amounts in most of the volcanic, sedimentary and metamorphic rocks.

Its more important minerals are ilmenite, rutile, arizonite (iron titanate), brookite, anatase, leucochene (titanium dioxide), perovskite (calcium titanate), and others. The first two have commercial importance, and can be found in deposits spread all over the world. There are important rutile and ilmenite deposits in Australia, Argentina, USA, Central Africa, Brazil, Canada, Egypt, India and Norway. The largest well-known deposits of rutile are located in Australia.

Titanium and its alloys are relatively new engineering metals since they have been in use only since about 1952. They are extremely attractive materials for engineers because they have a high strength to weight ratio, high elevated temperature properties to about 550^oC, and excellent corrosion resistance particularly in oxidising acids and chloride media.  This metal is being increasingly used for marine applications. Its resistance to seawater attack combined with its mechanical properties make it a prime choice for equipment operating within the sea or transferring seawater.

Titanium is not an 'exotic' metal, it is the fourth most abundant structural metal in the earth's crust, and the ninth industrial metal. This metal has become the prime selection for a wide range of critical and demanding applications.

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 1668^oC which is higher than iron at1560^oC. 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 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.

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 strengths up to 1345 x 10⁶ Pa.(Solution treated and age hardened)   Beta alloys are the smallest group. They are used for heavier duty purposes on aircraft.

The tables below are based on USA ASTM Grades which seem to be the most popular.   I also have information on CEN (European grades).  These are not as popular and I have not included them at this stage. This information is not detailed and I will attempt to improve its quality over time.   Please use the links below for better information.