Titanium alloys

[AirborneMetals]

Titanium alloys are classified as α, β, and α-β alloys. α-phase titanium is structured close-packed hexagonal and is the manifestation below 885 C, while β-phase is body-centered cubic persisting from 885 C to the melting point.

The α-β transition point may be influenced by adding alloying elements. α-stabilizers (like oxygen and aluminum) are elements raising the transition temperature while β-stabilizers (like manganese, chromium, iron, molybdenum, vanadium and niobium) have the opposite effect; in some cases they may do so to the extent of retention of some β-phase at room temperature.

In aerospace, Ti 6-4 (also known as Grade 5) is the most common alloy. It is a heat-treatable α-β alloy, containing 6% aluminum and 4% vanadium. It can be used up to approximately 400 degrees Centigrade and the alloy combines favorable properties like high strength, corrosion resistance, weldability and good machinability.