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Titanium was discovered by a keen mineral researcher Reverend William Gregor at the end of the 18th century, who found dark sand in Cornwall (UK) containing FeTiO3 oxide (ilmenite); then the chemist M.H. Klaproth identified the TiO2 oxide (rutile) in samples of sand originating in Hungary. The latter called this new element titanium, after the Titans in Greek mythology.
The high stability of titanium compounds with oxygen however, made it practically impossible to extract it from the minerals using traditional steel processing technologies. It was only at the start of the 20th century that Hunter and Kroll completed a process that produced pure titanium that could be used at an industrial scale.
The first step when producing sponge is the chlorination of the titanium containing mineral rutile or ilmenite. Chlorine and coke are combined with rutile to produce Titanium Tetrachloride, which then reacts with magnesium. The by-products are sponge and magnesium chloride. Using the vacuum distillation process, the magnesium and magnesium chloride are removed and recycled. The sponge is melted with scrap and binders to produce ingots in VACUUM ARC (VAR) furnaces.

Titanium is an allotropic elements with two structure types: the hexagonal close-packed lattice (HCP), called the alpha phase (T < 883°C), and a body-centred cubic lattice (BCC), called the alpha-beta phase (T>883°C).
The two structures depend on the type of alloy elements which influence the type of mechanical properties and consequently the final application: alpha-stabilising elements form in the presence of aluminium, oxygen, carbon and nitrogen; alpha-beta stabilising elements form in the presence of Iron, Chromium, Silice and Nickel, whilst Vanadium, Molybdenum and Niobio form isomorphous compounds with the alpha-beta phase. Other elements including Zirconium, Aphnium or Tin have no substantial effects on the β-transus temperature of the alloy in which they are present, but tend to improve the mechanical properties.

Titanium Wire and Bars
Titanium Tubes
Titanium Sheets
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Titanium is divided into a number of commercially pure grades as identified by the ASTM B265 code (Gr. 1,2,3,4,5,7,11,12). Each grade has a different amount of impurity content (Grade 1 has lowest impurities). Grade 1 to 4 is 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.

Grade 1: Titanium with low oxygen content. Suitable for deep drawing and cold deformation work. It exhibits excellent corrosion resistance. In addition, Titanium grade 1 can be easily welded, cold worked and hot worked.

Grade 2: Excellent formability and superior corrosion resistance.
It is slightly stronger than Ti Grade 1, makes it an ideal material for a large variety of chemical and marine application. It has a higher oxygen content than Grade 1. Widely used as it combines resistance, weldability and formability. 

Grade 3: Titanium with a higher oxygen content than Grade 1 and 2. Excellent weldability and used for pressure systems. It is a titanium with higher mechanical strength (typical yield strength 462 MPa). Moderate ductility and excellent weldability. Grade 3 titanium has a density of 4.51 g/cc - less than 60% that of steel.

Grade 4: Titanium with highest characteristics. It is used to produce medical and dental instruments and implants, in the watch and automation industries and many more. Grade 4 is the strongest of these grades with minimum yield strength of 480 MPa. This grade is suitable in applications where strength and corrosion resistance are important.

Grade 5: Titanium Alloy Gr 5 Ti6Al4V (Ti64) is the most widely used titanium alloy, it has high mechanical properties, but low ductility. Gr 5 is also classed as an alpha-beta alloy and most widely used in high strength applications including aerospace, offshore, marine and power generation.

Grade 7: Titanium Palladium Alloy Gr 7 (Ti Pd Alloy) is the most corrosion resistant of all currently available titanium alloys, this grade is especially well suited to applications requiring resistance to general as well as localized crevice corrosion.

Grade 9: This titanium alloy can be used in higher temperatures than commercially pure titanium grades 1-4, as it can be cold rolled with its excellent corrosion resistance capability its used in industrial, aerospace and sporting equipments.

The successful applications of Ti and Ti alloys in biomedical implants are without doubt thanks to the combination of excellent corrosion resistance performance in a physiological, biocompatibility and mechanical properties environment.
The limit to the diffusion of titanium alloys is represented by the high costs of the finished products, the processing and material costs makes the price at least one order of magnitude higher than that of stainless steel.

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