Titanium is a very remarkable metal. It has excellent mechanical properties (good fatigue strength, high resilience, resistance to heat and cryogenics, acceptable creep resistance, etc.) for a density of about 60% of that of steel (Dtitanium = 4.5 < Steel ≈ 7.8). Its specific strength (mechanical strength/ density ratio) is therefore higher than that of aluminum or steel.
In addition to its very good density, titanium has exceptional corrosion resistance (higher than that of stainless steels) even in the most aggressive environments. This resistance combined with its biocompatibility and low modulus of elasticity (110,000MPa) makes it an ideal metal for the medical field.
It should be noted that heat and mechanical treatments are carried out on titanium in order to modify its physico-chemical properties.
There are four classes of titanium alloys:
is mainly used in the chemical field for its corrosion resistance properties and its cold deformability. It has excellent weldability.
Example of grade: T40.
THE ALPHA ALLOYS α
also have excellent weldability but are difficult to cold-form and not heat-treatable. They are used for cryogenic applications, aerospace parts and in the chemical industry.
Example of grade: TA5E (TiAl5Sn2.5).
THE ALPHA-BETA ALLOYS α+β
offer the most possibilities due to their ability to be heat-treated, their compositions and therefore their different properties. They are used for aeronautical parts (structures, turbojets, etc.) or for marine and biomedical applications. On the other hand, they are more difficult to weld.
Example of grade: TA6V (TiAl6V4).
BETA ALLOYS β
offer an excellent combination of mechanical properties: hardness – ductility – fatigue resistance. They are weldable but nevertheless not heat-treatable. These alloys are mainly used for highly stressed structural aerospace parts..
Example of grade: Ti.10.2.3 (TiV10Fe2Al3).
=> A fifth category can also be defined: INTERMETALLIC TIAL COMPOUNDS. They are alloys of titanium, aluminum (generally between 45 and 48%) and additive elements. They are of interest for high temperature applications (aeronautics, automotive, etc.)
Example of grade: TiAl47Nb2Cr2.
However, the majority of titanium is used in the form of titanium dioxide (TiO2) which is an excellent pigment and/or thickener. It is subsequently used for paints, plastics, paper, cosmetics, sun creams, etc.