DRDO develops high strength titanium alloy for aerospace forgings

The Defence Research and Development Organisation (DRDO) has announced the indigenous development of a “high strength metastable beta titanium alloy” on Tuesday. This will be produced on an industrial scale for making aerospace structural forgings.

The alloy has been developed by the Hyderabad-based Defence Metallurgical Research Laboratory (DMRL), one of the DRDO’s premier laboratories that carries out fundamental research in the field of materials science and technology. DMRL’s specified role is to develop and productionise metals, alloys, ceramics and their composites for advanced uses, such as in aircraft engines and aerostructures.

DMRL has announced that the new alloy, in which titanium is alloyed with vanadium, iron and aluminium, has an extraordinarily high strength-to-weight ratio. Several advanced countries already use this to manufacture intricate aerospace components, with significant weight savings over the relatively heavier structural steels in which iron is alloyed with nickel, chromium and molybdenum.

“The high strength beta titanium alloys are unique due to their higher strength, ductility, fatigue, and fracture toughness – making them increasingly attractive for aircraft structural applications. Furthermore, their relatively lower lifetime cost, owing to superior corrosion resistance in comparison to steels, is an effective trade-off to justify the use of this expensive material in India,” stated a Ministry of Defence (MoD) press release.

Another DRDO laboratory – the Aeronautical Development Agency (ADA) which oversees the Tejas fighter programme – has already identified over 15 steel components which may be replaced by the new titanium alloy forgings, with weight savings up to 40 per cent.

“The landing gear drop link is the first component forged successfully by ADA at Hindustan Aeronautics Ltd, Bengaluru, with DMRL’s involvement and duly certified for airworthiness,” said the DRDO.

DMRL develops special steels and other super-alloys (such as those mixed with nickel) and then facilitates their commercial production by industrial units. In cases where only a small and commercially unviable quantity is required, DMRL works with defence public sector undertaking (DPSU), Mishra Dhatu Nigam (MIDHANI), to develop economically viable production techniques. 

In case the quantity required is high, such as for warship-grade steel, DMRL productionises the material through a non-defence, commercial unit, e.g. Steel Authority of India Ltd (SAIL).

Essentially, DMRL translates laboratory experiments into commercial production. This requires developing techniques to produce large batches entirely homogenously. 

“Productionisation means going from producing in kilos to producing in tons,” says a senior DMRL scientist.

In this case, “DMRL has carried out raw material selection, alloy melting, thermo-mechanical processing, ultrasonics-based Non Destructive Evaluation (NDE), heat treatment, mechanical characterization, and type certification in active collaboration with several agencies,” said the DRDO.