Ti-6Al-4V (UNS designation R56400), also sometimes called TC4, Ti64, or ASTM Grade 5, is an alpha-beta

titanium alloy 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 ...

with a high

specific strength The specific strength is a material's (or muscle's) strength (force per unit area at failure) divided by its density. It is also known as the strength-to-weight ratio or strength/weight ratio or strength-to-mass ratio. In fiber or textile applic ...

and excellent

corrosion resistance Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...

. It is one of the most commonly used titanium alloys and is applied in a wide range of applications where low density and excellent corrosion resistance are necessary such as the

aerospace industry Aerospace is a term used to collectively refer to the atmosphere and outer space. Aerospace activity is very diverse, with a multitude of commercial, industrial, and military applications. Aerospace engineering consists of aeronautics and astr ...

and biomechanical applications (implants and

prostheses In medicine, a prosthesis (: prostheses; from ), or a prosthetic implant, is an artificial device that replaces a missing body part, which may be lost through physical trauma, disease, or a condition present at birth (congenital disorder). Prosthe ...

). Studies of titanium alloys used in armors began in the 1950s at the

Watertown Arsenal The Watertown Arsenal was a major American arsenal located on the northern shore of the Charles River in Watertown, Massachusetts. The site is now registered on the American Society of Civil Engineers, ASCE's List of Historic Civil Engineeri ...

, which later became a part of the

Army Research Laboratory The U.S. Army Combat Capabilities Development Command Army Research Laboratory (DEVCOM ARL) is the foundational research laboratory for the United States Army under the United States Army Futures Command (AFC). DEVCOM ARL conducts intramural an ...

. A 1948 graduate of MIT, Stanley Abkowitz (1927–2017) was a pioneer in the titanium industry and is credited for the invention of the Ti-6Al-4V during his time at the US Army’s Watertown Arsenal Laboratory in the early 1950s. Titanium/Aluminum/Vanadium alloy was hailed as a major breakthrough with strategic military significance. It is the most commercially successful titanium alloy and is still in use today, having shaped numerous industrial and commercial applications. Increased use of titanium alloys as biomaterials is occurring due to their lower modulus, superior biocompatibility and enhanced corrosion resistance when compared to more conventional stainless steels and cobalt-based alloys. These attractive properties were a driving force for the early introduction of α (cp-Ti) and α+β (Ti-6Al-4V) alloys as well as for the more recent development of new Ti-alloy compositions and orthopaedic metastable b titanium alloys. The latter possess enhanced biocompatibility, reduced elastic modulus, and superior strain-controlled and notch fatigue resistance. However, the poor shear strength and wear resistance of titanium alloys have nevertheless limited their biomedical use. Although the wear resistance of b-Ti alloys has shown some improvement when compared to a#b alloys, the ultimate utility of orthopaedic titanium alloys as wear components will require a more complete fundamental understanding of the wear mechanisms involved.

Chemistry

(in wt. %)

Physical and mechanical properties

Ti-6Al-4V titanium alloy commonly exists in alpha, with hcp crystal structure, (SG : P63/mmc) and beta, with bcc crystal structure, (SG : Im-3m) phases. While mechanical properties are a function of the heat treatment condition of the alloy and can vary based upon properties, typical property ranges for well-processed Ti-6Al-4V are shown below.

Aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

stabilizes the alpha phase, while

vanadium Vanadium is a chemical element; it has Symbol (chemistry), symbol V and atomic number 23. It is a hard, silvery-grey, malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an ...

stabilizes the beta phase. Ti-6Al-4V has a very low

thermal conductivity The thermal conductivity of a material is a measure of its ability to heat conduction, conduct heat. It is commonly denoted by k, \lambda, or \kappa and is measured in W·m−1·K−1. Heat transfer occurs at a lower rate in materials of low ...

at room temperature of 6.7 to 7.5 W/m·K, which contributes to its relatively poor machinability. The alloy is vulnerable to

cold dwell fatigue Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjective perception. A lower bound to temperature is absolute zero, defined as 0.00K on the Kelvin scale, an absolute thermodynamic ...

Heat treatment of Ti-6Al-4V

Common Ti-6Al-4V Heat Treatment Processes

Ti-6Al-4V is heat treated to vary the amounts of and microstructure of

\alpha

and

\beta

phases in the alloy. The microstructure will vary significantly depending on the exact heat treatment and method of processing. Three common heat treatment processes are mill annealing, duplex annealing, and solution treating and aging.

Applications

* Aerospace structures. The

Boeing 787 The Boeing 787 Dreamliner is an American wide-body airliner developed and manufactured by Boeing Commercial Airplanes. After dropping its unconventional Sonic Cruiser project, Boeing announced the conventional 7E7 on January 29, 2003, wh ...

is 15% titanium by weight, and the

Airbus A350 The Airbus A350 is a flight length, long-range, wide-body twin-engine airliner developed and produced by Airbus. The initial A350 design proposed in 2004, in response to the Boeing 787 Dreamliner, would have been a development of the Airbu ...

is 14%. * Biomedical implants and prostheses. * High-performance race cars. * High-end bicycles. * Additive manufacturing. *Marine applications: Ti-6Al-4V Grade 5 is extensively used in marine applications due to its exceptional

corrosion Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...

resistance in seawater environments. Ti-6Al-4V is applied in components exposed to marine atmospheres and underwater conditions, such as

shipbuilding Shipbuilding is the construction of ships and other Watercraft, floating vessels. In modern times, it normally takes place in a specialized facility known as a shipyard. Shipbuilders, also called shipwrights, follow a specialized occupation th ...

offshore oil Offshore drilling is a mechanical process where a wellbore is drilled below the seabed. It is typically carried out in order to explore for and subsequently extract petroleum that lies in rock formations beneath the seabed. Most commonly, the te ...

and gas platforms, and subsea equipment. Its resistance to

helps in reducing maintenance costs and extending the lifespan of marine equipment.

Specifications

* UNS: R56400 * AMS Standard: 4928 * ASTM Standard: F1472 * ASTM Standard: B265 Grade 5

References

{{Reflist Titanium alloys