Ti-6Al-4V

Ti-6Al-4V (UNS designation R56400), also sometimes called TC4, Ti64, or ASTM Grade 5, is an alpha-beta titanium alloy with a high specific strength and excellent corrosion resistance. It is one of the most commonly used titanium alloys and is applied in a wide range of applications where high strength, low density, and excellent corrosion resistance are necessary, such as in aerospace and biomechanical implants and prostheses.

Backscattered electron micrograph of polished Ti-6Al-4V with an equiaxed microstructure. Dark grains are HCP alpha phase and light ones are BCC beta phase.
Backscattered electron micrograph of polished Ti-6Al-4V with an equiaxed microstructure. Dark grains are HCP alpha phase and light ones are BCC beta phase.

Studies of titanium alloys used in armor began in the 1950s at the Watertown Arsenal, which later became a part of the Army Research Laboratory.

A 1948 graduate of MIT, Stanley Abkowitz 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 alloys are used in implanted medical devices due to their lower modulus[which?], higher biocompatibility, and better corrosion resistance than stainless steels and cobalt-based alloys. These 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, a reduced elastic modulus[which?], and superior strain-controlled and notch fatigue resistance. However, the poor shear strength and wear resistance of titanium alloys have limited their biomedical use. The wear resistance of b-Ti alloys has shown some improvement when compared to a#b alloys.

Chemistry

(in wt. %)

VAlFeOCNHYTiRemainder EachRemainder Total
Min3.55.5------------------
Max4.56.75.3.2.08.05.015.005Balance.1.3

Physical and mechanical properties

One possible microstructure of Ti-6Al-4V alloy with equiaxed alpha grains and discontinuous beta phase

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 stabilizes the alpha phase, while vanadium stabilizes the beta phase.

DensityYoung's ModulusShear ModulusBulk ModulusPoisson's RatioTensile Yield StressTensile Ultimate StressHardnessUniform Elongation
Min4.429 g/cm3 (0.160 lb/cu in)104 GPa (15.1×10^6 psi)40 GPa (5.8×10^6 psi)96.8 GPa (14.0×10^6 psi)0.31880 MPa (128,000 psi)900 MPa (130,000 psi)36 Rockwell C (Typical)5%
Max4.512 g/cm3 (0.163 lb/cu in)113 GPa (16.4×10^6 psi)45 GPa (6.5×10^6 psi)153 GPa (22.2×10^6 psi)0.37920 MPa (133,000 psi)950 MPa (138,000 psi)--18%

Ti-6Al-4V has a very low thermal conductivity 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.

Heat treatment of Ti-6Al-4V

Mill anneal, duplex anneal, and solution treatment and aging heat treatment processes for Ti-6Al-4V. Exact times and temperatures will vary by manufacturer.

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

Specifications

References

  1. ↑ Paul K. Chu; XinPei Lu (15 July 2013). Low Temperature Plasma Technology: Methods and Applications. CRC Press. p. 455. ISBN 978-1-4665-0991-7.
  2. ↑ "Founding of ARL". www.arl. army.mil. Army Research Laboratory. Retrieved 6 June 2018.
  3. ↑ Gooch, William A. "The Design and Application of Titanium Alloys to U.S. Army Platforms -2010" (PDF). U.S. Army Research Laboratory. Retrieved 6 June 2018.
  4. ↑ "Stan Abkowitz, '48 – MIT Technology Review". 18 October 2016.
  5. ↑ Long, M.; Rack, H.J. (1998). "Titanium alloys in total joint replacement—a materials science perspective". Biomaterials. 18 (19): 1621–1639. doi:10.1016/S0142-9612(97)00146-4. PMID 9839998.
  6. ↑ Gutmanas, E.Y.; Gotman, I. (2004). "PIRAC Ti nitride coated Ti–6Al–4V head against UHMWPE acetabular cup–hip wear simulator study". Journal of Materials Science: Materials in Medicine. 15 (4): 327–330. doi:10.1023/B:JMSM.0000021096.77850.c5. PMID 15332594. S2CID 45437647.
  7. ↑ Standard Specification for Wrought Titanium-6Aluminum-4Vanadium Alloy for Surgical Implant Applications (UNS R56400)
  8. ↑ "Titanium Ti-6Al-4V (Grade 5), Annealed". asm.matweb.com. ASM Aerospace Specification Metals, Inc. Retrieved 14 March 2017.
  9. ↑ "Titanium Alloy Ti 6Al-4V Technical Data Sheet". stainless.eu. Stainless Group. Retrieved 6 June 2026.
  10. ↑ "AZoM Become a Member Search... Search Menu Properties This article has property data, click to view Titanium Alloys - Ti6Al4V Grade 5". www.azom.com. AZO Materials. 30 July 2002. Retrieved 14 March 2017.
  11. ↑ Wanhill, Russell; Barter, Simon (2012), "Metallurgy and Microstructure", Fatigue of Beta Processed and Beta Heat-treated Titanium Alloys, Springer Netherlands, pp. 5–10, doi:10.1007/978-94-007-2524-9_2, ISBN 9789400725232
  12. ↑ Donachie, Matthew J. (2000). Titanium : a technical guide (2nd ed.). Materials Park, OH: ASM International. pp. 13–15. ISBN 9781615030620. OCLC 713840154.
  13. ↑ "ASM Material Data Sheet". asm.matweb.com. Retrieved 2020-06-20.
  14. 1 2 Yang, Xiaoping; Liu, C. Richard (1999-01-01). "Machining Titanium and Its Alloys". Machining Science and Technology. 3 (1): 107–139. doi:10.1080/10940349908945686. ISSN 1091-0344.
  15. ↑ BEA (September 2020). "AF066 crash investigation results" (PDF).
  16. ↑ Pilchak, Adam L.; Hutson, Alisha; Porter, W. John; Buchanan, Dennis; John, Reji (2016). "On the Cyclic Fatigue and Dwell Fatigue Crack Growth Response of Ti-6Al-4V". Proceedings of the 13th World Conference on Titanium. pp. 993–998. doi:10.1002/9781119296126.ch169. ISBN 9781119296126.
  17. ↑ ASM Committee (2000). "The Metallurgy of Titanium". Titanium: A Technical Guide. ASM International. pp. 22–23.
  18. ↑ Hawk, Jeff (May 25, 2005). The Boeing 787 Dreamliner: More Than an Airplane (PDF). AIAA/AAAF Aircraft Noise and Emissions Reduction Symposium. American Institute of Aeronautics and Astronautics. Archived from the original (PDF) on August 8, 2007. Retrieved July 15, 2007.
  19. ↑ Guy Hellard (2008). "Composites in Airbus - A Long Story of Innovations and Experiences" (PDF). Global Investor Forum. Airbus. Archived from the original (PDF) on 4 October 2016. Retrieved 30 January 2019.
  20. ↑ "Ti6Al4V Titanium Alloy" (PDF). Arcam. Archived from the original (PDF) on 2020-02-15. Retrieved 2015-12-16.
  21. ↑ "Demystifying Titanium Alloys: TI 6-4 Grade 5 VS. TI 23". Stanford Advanced Materials. Retrieved June 30, 2024.
  22. ↑ Sorkin, G.; Lane, I.R.; Cavallaro, J.L. (1982). "Ti-6A1-4V for Marine Uses". In Williams, J.C (ed.). Titanium and Titanium Alloys. Springer. pp. 2139–2147. doi:10.1007/978-1-4757-1758-7_49. ISBN 978-1-4757-1760-0.
  23. ↑ Gurrappa, I. (2003). "Characterization of titanium alloy Ti-6Al-4V for chemical, marine and industrial applications". Materials Characterization. 51 (2–3): 131–139. doi:10.1016/j.matchar.2003.10.006.
  24. ↑ Alijibori, H.S.; Alamiery, A.; Kadhum, A.A.H. (2023). "Advances in corrosion protection coatings: A comprehensive review". Int. J. Corros. Scale Inhib. 12 (4): 1476–1520. doi:10.17675/2305-6894-2023-12-4-6.
  25. ↑ "iPhone Air". Apple. Apple Inc. Retrieved 2026-07-14.
  26. ↑ SAE AMS4928W, Titanium Alloy Bars, Wire, Forgings, Rings, and Drawn Shapes 6Al - 4V Annealed, Warrendale, PA: SAE International, retrieved 28 September 2022
  27. ↑ "§1.1.5", ASTM B265-20a, Standard Specification for Titanium and Titanium Alloy Strip, Sheet, and Plate, West Conshohocken, PA: ASTM International, 2020, doi:10.1520/B0265-20A, retrieved 13 August 2020