Titanium is used in steel as an alloying element (ferro-titanium) to reduce grain size and as a deoxidizer, and in stainless steel to reduce carbon content.[3] Titanium is often alloyed with aluminium (to refine grain size), vanadium, copper (to harden), iron, manganese, molybdenum, and with other metals.[57] Applications for titanium mill products (sheet, plate, bar, wire, forgings, castings) can be found in industrial, aerospace, recreational, and emerging markets. Powdered titanium is used in pyrotechnics as a source of bright-burning particles.

Aerospace and marine

Due to their high tensile strength to density ratio,[8] high corrosion resistance,[4] fatigue resistance, high crack resistance,[59] and ability to withstand moderately high temperatures without creeping, titanium alloys are used in aircraft, armor plating, naval ships, spacecraft, and missiles.[4][5] For these applications titanium alloyed with aluminium, zirconium, nickel,[60] vanadium, and other elements is used for a variety of components including critical structural parts, fire walls, landing gear, exhaust ducts (helicopters), and hydraulic systems. In fact, about two thirds of all titanium metal produced is used in aircraft engines and frames.[61] The SR-71 "Blackbird" was one of the first aircraft to make extensive use of titanium within its structure, paving the way for its use in modern military and commercial aircraft. An estimated 59 metric tons (130,000 pounds) are used in the Boeing 777, 45 in the Boeing 747, 18 in the Boeing 737, 32 in the Airbus A340, 18 in the Airbus A330, and 12 in the Airbus A320. The Airbus A380 may use 77 metric tons, including about 11 tons in the engines.[62] In engine applications, titanium is used for rotors, compressor blades, hydraulic system components, and nacelles. The titanium 6AL-4V alloy accounts for almost 50% of all alloys used in aircraft applications.[63]

Due to its high corrosion resistance to sea water, titanium is used to make propeller shafts and rigging and in the heat exchangers of desalination plants;[4] in heater-chillers for salt water aquariums, fishing line and leader, and for divers' knives. Titanium is used to manufacture the housings and other components of ocean-deployed surveillance and monitoring devices for scientific and military use. The former Soviet Union developed techniques for making submarines with hulls of titanium alloys.[64] Techniques were developed in the Soviet Union to forge titanium in huge vacuum tubes.[60]

Industrial

High-purity (99.999%) titanium with visible crystallites

Welded titanium pipe and process equipment (heat exchangers, tanks, process vessels, valves) are used in the chemical and petrochemical industries primarily for corrosion resistance. Specific alloys are used in downhole and nickel hydrometallurgy applications due to their high strength (e. g.: titanium Beta C alloy), corrosion resistance, or combination of both. The pulp and paper industry uses titanium in process equipment exposed to corrosive media such as sodium hypochlorite or wet chlorine gas (in the bleachery).[65] Other applications include: ultrasonic welding, wave soldering,[66] and sputtering targets.[67]

Titanium tetrachloride (TiCl4), a colorless liquid, is important as an intermediate in the process of making TiO2 and is also used to produce the Ziegler-Natta catalyst. Titanium tetrachloride is also used to iridize glass and, because it fumes strongly in moist air, it is used to make smoke screens.[10]

Consumer and architectural

Titanium metal is used in automotive applications, particularly in automobile or motorcycle racing, where weight reduction is critical while maintaining high strength and rigidity.[68] The metal is generally too expensive to make it marketable to the general consumer market, other than high-end products, particularly for the racing/performance market. Some late model Corvettes have been available with titanium exhausts,[69] and the new Corvette Z06's LT4 supercharged engine uses lightweight, solid titanium intake valves for greater strength and resistance to heat.[70]

Titanium is used in many sporting goods: tennis rackets, golf clubs, lacrosse stick shafts; cricket, hockey, lacrosse, and football helmet grills; and bicycle frames and components. Although not a mainstream material for bicycle production, titanium bikes have been used by race teams and adventure cyclists.[71] Titanium alloys are also used in spectacle frames.[72] This results in a rather expensive, but highly durable and long lasting frame which is light in weight and causes no skin allergies. Many backpackers use titanium equipment, including cookware, eating utensils, lanterns, and tent stakes.[72] Though slightly more expensive than traditional steel or aluminium alternatives, these titanium products can be significantly lighter without compromising strength. Titanium is also favored for use by farriers, because it is lighter and more durable than steel when formed into horseshoes.[72]

Titanium has occasionally been used in architectural applications: the 40 m (131 foot) memorial to Yuri Gagarin, the first man to travel in space, in Moscow (55°42′29.7″N 37°34′57.2″E), is made of titanium for the metal's attractive color and association with rocketry.[73] The Guggenheim Museum Bilbao and the Cerritos Millennium Library were the first buildings in Europe and North America, respectively, to be sheathed in titanium panels.[61] Other construction uses of titanium sheathing include the Frederic C. Hamilton Building in Denver, Colorado[74] and the 107 m (350 foot) Monument to the Conquerors of Space in Moscow.[75]

Because of its superior strength and light weight when compared to other metals traditionally used in firearms (steel, stainless steel, and aluminium), and advances in metalworking techniques, the use of titanium has become more widespread in the manufacture of firearms. Primary uses include pistol frames and revolver cylinders. For these same reasons, it is also used in the body of laptop computers (for example, in Apple's PowerBook line).[76]

Some upmarket categories of tools made to be lightweight and corrosion-resistant, such as shovels and flashlights, are made of titanium or titanium alloys as well.

Jewelry

Because of its durability, titanium has become more popular for designer jewelry (particularly, titanium rings).[72] Its inertness makes it a good choice for those with allergies or those who will be wearing the jewelry in environments such as swimming pools. Titanium is also alloyed with gold to produce an alloy that can be marketed as 24-carat gold, as the 1% of alloyed Ti is insufficient to require a lesser mark. The resulting alloy is roughly the hardness of 14-carat gold and thus is more durable than a pure 24-carat gold item would be.[77]

Titanium's durability, light weight, dent- and corrosion resistance makes it useful in the production of watch cases.[72] Some artists work with titanium to produce artworks such as sculptures, decorative objects and furniture.[78]

The inertness and ability to be attractively colored makes titanium a popular metal for use in body piercing.[79] Titanium may be anodized to produce various colors, which varies the thickness of the surface oxide layer and causes interference fringes.[80]

Titanium has a minor use in dedicated non-circulating coins and medals. In 1999 Gibraltar released world's first titanium coin for the millennium celebration.[81] The Gold Coast Titans, an Australian rugby league team, award a medal of pure titanium to their player of the year.[82]

Medical

Titanium biocompatibility: Because it is biocompatible (it is non-toxic and is not rejected by the body), titanium has many medical uses, including surgical implements and implants, such as hip balls and sockets (joint replacement) that can stay in place for up to 20 years.[34] The titanium is often alloyed with about 4% aluminium or 6% Al and 4% vanadium.[83]

Titanium has the inherent ability to osseointegrate, enabling use in dental implants that can last for over 30 years. This property is also useful for orthopedic implant applications.[34] These benefit from titanium's lower modulus of elasticity (Young's modulus) to more closely match that of the bone that such devices are intended to repair. As a result, skeletal loads are more evenly shared between bone and implant, leading to a lower incidence of bone degradation due to stress shielding and periprosthetic bone fractures, which occur at the boundaries of orthopedic implants. However, titanium alloys' stiffness is still more than twice that of bone, so adjacent bone bears a greatly reduced load and may deteriorate.[84]

Because titanium is non-ferromagnetic, patients with titanium implants can be safely examined with magnetic resonance imaging (convenient for long-term implants). Preparing titanium for implantation in the body involves subjecting it to a high-temperature plasma arc which removes the surface atoms, exposing fresh titanium that is instantly oxidized.[34]

Titanium is also used for the surgical instruments used in image-guided surgery, as well as wheelchairs, crutches, and any other products where high strength and low weight are desirable.

Nuclear waste storage

Due to its extreme corrosion resistance, titanium containers have been studied for the long-term storage of nuclear waste (containers lasting over 100,000 years are possible under proper manufacturing conditions to reduce defects in the process).[85] A titanium "drip shield" could also be placed over other types of containers to further contain the waste.