Titanium Alloys
Titanium alloys are alloys that contain a mixture of titanium and other
chemical elements.
Such alloys have very high tensile strength and toughness (even at extreme
temperatures). They are light in weight, have extraordinary corrosion resistance
and the ability to withstand extreme temperatures. However, the high cost of
both raw materials and processing limit their use to military applications,
aircraft, spacecraft, bicycles, medical devices, jewelry, highly stressed
components such as connecting rods on expensive sports cars and some premium
sports equipment and consumer electronics.
Although "commercially pure" titanium has acceptable mechanical properties and
has been used for orthopedic and dental implants, for most applications titanium
is alloyed with small amounts of aluminium and vanadium, typically 6% and 4%
respectively, by weight. This mixture has a solid solubility which varies
dramatically with temperature, allowing it to undergo precipitation
strengthening. This heat treatment process is carried out after the alloy has
been worked into its final shape but before it is put to use, allowing much
easier fabrication of a high-strength product.
Types of alloys
There are two main types of alloyed aluminium; wrought and cast. Wrought alloys
(rolled, extruded or forged) are strengthened either by work–hardening or by
heat treatment, with different alloying elements being added to achieve the
required strength. Cast alloys are usually very different in their composition
to their wrought counterparts, as suitable composition is required for the
production of effective casting materials. The wrought alloys are also divided
into two groups: heat-treatable and non heat-treatable alloys. Heat-treatable
alloys are produced in the main for their strength and durability while the non
heat-treatable alloys for their ductility, weldability and corrosion
resistance.
Alloy Specifications
All alloys are given a specification number and a combination of letters and
numbers that are placed after this specification number to indicate the
strengthening process undergone by the metal. For example, the alloy
specification 6082 often carries the definition T6 – this indicates that it is
solution treated and artificially aged (also known as “fully heat treated”),
while alloy 2011 often carries the T3 definition, indicating it has been
solution heat treated, cold worked and naturally aged to a substantially stable
condition.