The Defence Research and Development Organisation (DRDO) has developed single crystal blades technology and has supplied 60 of these blades to Hindustan Aeronautics Ltd (HAL) as part of their indigenous helicopter development programme for helicopter engine application.This is part of a programme taken up by the Defence Metallurgical Research Laboratory (DMRL), a premium laboratory of the DRDO, to develop 5 sets (300 numbers) of single crystal high pressure turbine (HPT) blades using a nickel-based super alloy. The supply of remaining 4 sets will be completed in due course, the DRDO said on Monday.Helicopters, used in strategic and defence applications, need compact and powerful aero-engines for their reliable operation at extreme conditions. To achieve this, state-of-the-art single crystal blades having complex shape and geometry, manufactured out of nickel-based superalloys capable of withstanding high temperatures of operation are used. Very few countries in the world such as the US, the UK, France, and Russia have the capability to design and manufacture such single crystal (SX) components.
The DMRL undertook this task based on its expertise gained during the development of such a technology for a aero-engine project earlier. Complete vacuum investment casting process to realise the blades, including die design, wax pattering, ceramic moulding, actual casting of components non-destructive evaluation (NDE), heat treatment and dimensional measurement, has been established at the DMRL.Special ceramic composition had to be formulated for making strong ceramic moulds which can withstand metallostatic pressure of liquid CMSX-4 alloy at 1,500 degrees Celsius and above during casting operation. The challenge of maintaining the required temperature gradient has also been overcome by optimizing the casting parameters. A multi-step vacuum solutionising heat treatment schedule for complex CMSX-4 superalloy to achieve the required microstructure and mechanical properties has also been established.Further, a stringent non-destructive evaluation (NDE) methodology for the blades along with the technique for determining their crystallographic orientations has been developed.Defence Minister Rajnath Singh congratulated the DRDO, the HAL and industry involved in the development of critical technology.Secretary, R&D in Defence Ministry and DRDO Chairman, Dr G. Satheesh Reddy also congratulated and appreciated the efforts involved in indigenous development of this vital technology.