What Is the Common Name for Ti-6Al-4V?
The most widely recognized common name for the titanium alloy Ti-6Al-4V is Grade 5 titanium, frequently shortened to Ti Grade 5 in industrial contexts. This designation is not arbitrary; it is defined by global material standards such as ASTM B265 for titanium sheet and plate, ASTM B348 for titanium bars and billets, and AMS 4928 for aerospace-grade Ti-6Al-4V, which classify the alloy on the basis of composition and performance. Unlike pure titanium grades such as Grade 2 or other titanium alloys, the Grade 5 label is universally understood in manufacturing, supply chains and engineering design to refer specifically to the 6Al-4V composition.
Why Grade 5 Is the Most Widely Used Titanium Alloy
Ti-6Al-4V earns its status as Grade 5 because it is the most versatile and widely used titanium alloy worldwide. Its composition, 6% aluminum which enhances strength and stability, and 4% vanadium which improves ductility and reduces brittleness, strikes an exceptional balance of mechanical properties and corrosion resistance. It offers a high strength-to-weight ratio and good fatigue resistance, making it indispensable in aerospace components such as aircraft engine parts and airframe structures, medical devices such as orthopedic implants and dental abutments, high-performance automotive parts, and corrosion-resistant marine engineering components.
Yield Strength of Ti-6Al-4V by Processing State
Yield strength represents the stress at which the material begins to deform permanently rather than only elastically, and for Ti-6Al-4V it varies significantly with processing state:
Annealed Ti-6Al-4V. Annealing heats the alloy below its beta transus, typically 700-800 degrees Celsius, followed by slow cooling, producing a uniform alpha-beta microstructure with improved ductility. Typical yield strength is 860-930 MPa, and standard specifications for annealed sheet and plate set minimum requirements that the material must meet.
Solution-treated and aged (STA) Ti-6Al-4V. STA solution-treats above the beta transus, approximately 995 degrees Celsius, quenches to trap the beta phase, then ages at 480-595 degrees Celsius to precipitate fine alpha particles within the beta matrix. Typical yield strength is 1,030-1,100 MPa, and AMS 4928 requires a minimum yield strength of about 1,034 MPa for aerospace STA material.
Hot-worked Ti-6Al-4V. Hot working, such as forging and rolling above about 600 degrees Celsius, refines the grain structure while the alloy is ductile. Typical yield strength of 900-980 MPa falls between the annealed and STA states.
Tensile Strength of Ti-6Al-4V by Processing State
Tensile strength, or ultimate tensile strength, is the maximum stress a material can withstand before fracturing under tension. Typical values by processing state are:
Annealed: 930-1,000 MPa, with standard requirements setting a minimum for annealed sheet and plate; this state prioritizes ductility and toughness.
Solution-treated and aged: 1,100-1,170 MPa, the highest of the common states, with AMS 4928 requiring a minimum of about 1,103 MPa; this state is chosen for aerospace fasteners and high-load components.
Hot-worked: 980-1,050 MPa, higher than annealed but lower than STA.
Minor variations can occur between manufacturers because of differences in raw material purity, processing parameters and testing methods such as tensile specimen geometry per ASTM E8, so the mill certificate should always be checked against the required values.
What Processing State Should You Choose?
Choose the annealed condition when ductility, toughness and weldability matter most, such as in formed airframe structures and corrosion-service components. Choose STA when maximum strength is required, such as aerospace fasteners, actuators and medical implants. Choose hot-worked material when the product form is a forging or bar whose grain structure has been refined during production and intermediate strength is acceptable. Confirm the governing specification, ASTM B265 for sheet and plate, B348 for bar, or AMS 4928 for aerospace, before ordering.
FAQ
What is the common name for Ti-6Al-4V?
Ti-6Al-4V is commonly called Grade 5 titanium, or Ti Grade 5, which is the standard designation used in ASTM and AMS specifications for this alpha-beta titanium alloy.
Why is Ti-6Al-4V called Grade 5?
The ASTM grade system numbers commercially pure and alloyed titanium products, and the 6Al-4V alloy was assigned Grade 5 because of its composition and broad acceptance as the workhorse titanium alloy.
What is the yield strength of annealed Ti-6Al-4V?
Annealed Ti-6Al-4V typically shows a yield strength of about 860-930 MPa depending on product form, while solution-treated and aged material reaches roughly 1,030-1,100 MPa.
Is Grade 5 titanium suitable for medical implants?
Yes. Ti-6Al-4V ELI, a lower-interstitial version of Grade 5, is widely used for orthopedic implants and dental components because of its biocompatibility, corrosion resistance and fatigue strength.
Can Ti-6Al-4V be welded?
Yes, but it requires clean conditions and inert gas shielding. The annealed condition is preferred for welding, because STA material can lose strength in the heat-affected zone, and post-weld heat treatment is often needed to restore properties.
What is the difference between Grade 2 and Grade 5 titanium?
Grade 2 is commercially pure titanium with lower strength but excellent formability and corrosion resistance, while Grade 5 (Ti-6Al-4V) is an alpha-beta alloy offering roughly double the strength, at higher cost and with more demanding processing.
