Titanium is a white metal, and has the best strength to weight ratio among the
metals. Titanium is very reactive, and because of this it is often used for alloying
and deoxidizing other metals. Titanium is a more powerful deoxidizer of steel
than silicon or manganese. Titanium is 40% lighter than steel and 60% heavier
than aluminum. This combination of high strength and low weight makes
titanium a very useful structural metal. Titanium also features excellent
corrosion resistance, which stems from a thin oxide surface film which protects
it from atmospheric and ocean conditions as well as a wide variety of chemicals.
Titanium is rather difficult to fabricate because of its susceptibility to oxygen,
nitrogen, and hydrogen impurities which cause the titanium to become more
brittle. Elevated temperature processing must be used under special conditions
in order to avoid diffusion of these gasses into the titanium. Commercially
produced titanium products are made in the following mill wrought forms; plate,
tubing, sheet, wire, extrusions, and forgings. Titanium can also be cast, which
must be done in a vacuum furnace because of titanium's reactive nature.
Because of its high strength to weight ratio, titanium is used in a variety of
applications, including products where weight is of importance such as
aircraft, sporting equipment, etc.. Because of its excellent corrosion resistance,
titanium is also used for chemical processing, desalination, power generation
equipment, valve and pump parts, marine hardware, and prosthetic devices.
|Commercially Pure Alloys:
There are five grades of what is known as commercially pure or unalloyed titanium, ASTM
Grades 1 through 4, and 7. Each grade has a different amount of impurity content, with Grade 1
being the most pure. Tensile strengths vary from 172 MPa for Grade 1 to 483 MPa for Grade 4.
Titanium alpha alloys are alloys that typically contain aluminum and tin, though they can also
contain molybdenum, zirconium, nitrogen, vanadium, columbium, tantalum, and silicon. Alpha
alloys do not generally respond to heat treatment, but they are weldable and are commonly used for
cryogenic applications, airplane parts, and chemical processing equipment.
Alpha-beta alloys can be strengthened by heat treatment and aging, and therefore can undergo
manufacturing while the material is still ductile, then undergo heat treatment to strengthen the
material, which is a big advantage. The alloys are used in aircraft and aircraft turbine parts, chemical
processing equipment, marine hardware, and prosthetic devices.
The smallest group of titanium alloys, beta alloys have good hardenability, good cold formability
when they are solution-treated, and high strength when they are aged. Beta alloys are slightly more
dense than other titanium alloys, having densities ranging from 4840 to 5060 kg/m3. They are the
least creep resistant alloys, they are weldable, and can have yield strengths up to 1345 MPa. They are
used for heavier duty purposes on aircraft.