High Strength β Titanium Alloys for Aerospace Structural Sheet Application

High strength beta titanium alloys due to their higher strength, ductility, fatigue and fracture toughness are used for aircraft structural applications and can replace steel which leads to considerable weight saving. Although costly, their lifetime costs are lower due to their superior corrosion resistance as compared to steel. Indian missile and the aircraft industry are looking for a titanium alloy which is amenable to cold rolling so that parts can be formed from it easily and also possess medium temperature strength. Currently available alloys, OT4‐1 and Ti64 are not very amenable to cold reduction.

Technology Developed at DMRL

DMRL has developed and established indigenous industrial scale manufacturing technology (melting and processing) for a beta titanium alloy Ti‐15Mo‐3Nb‐3Al‐0.3Fe‐0.2Si (Beta 21S) for aircraft structural applications. The Beta 21S (Titan 44) alloy possesses very good oxidation resistance along with good creep resistance. It can easily be formed into complicated shapes in beta solution treated condition and then can be aged to attain higher strength levels. The full manufacturing technology for raw material selection, alloy melting, thermo‐mechanical processing, cold rolling, heat treatment, mechanical property evaluation and type certification for cold rolled sheets of 2 mm, 1.2 mm and 0.8 mm in thickness has been established with DMRL know‐how.

Tensile Properties of Titan 44 at 2 mm Stage ‐ β Solution Treated & Aged (593 °C/8 h/AC)

Applications