DRDO lab develops crucial aero-engine forging technology

The HPC discs made out of titanium alloy by the DMRL.

India’s quest for expertise in the domain of aero-engine technologies got a boost on May 28 with the Defence Metallurgical Research Laboratory (DMRL) announcing the development of “isothermal forging technology” to manufacture all the five stages of high-pressure compressor (HPC) discs out of difficult-to-deform titanium alloy. The process uses DMRL’s unique 2000 MT isothermal forge press.

The development of the technology by the DMRL, a premier metallurgical laboratory in Hyderabad and a constituent of the Defence Research and Development Organisation (DRDO), catapults India into the league of a limited global engine developers who have the know-how to manufacture such critical aero-engine components.

DMRL has already supplied 200 indigenously manufactured HPC disc forgings to the defence public sector enterprise (DPSE) Hindustan Aeronautics Limited’s (HAL’s) Engine Division. These HPC disc forgings are being fitted in the Adour engine, the engine that powers the Indian Air Force’s (IAF’s) deep penetration Jaguar strike aircraft and the Hawk advanced jet trainers.

Officials from DMRL confirmed that both the IAF and HAL had, based on the exhaustive component level and performance evaluation test results, cleared the components for fitment in the Ardour engine. In India, the Adour engine is overhauled by HAL’s Engine Division under a licensed manufacturing agreement with Rolls-Royce Turbomeca, the Anglo-French joint venture.

While the initial batch of 200 HPC disc forgings were produced jointly by DMRL and Mishra Dhatu Nigam Limited (MIDHANI), the DPSE that produces various super alloys, special steels and materials for defence, nuclear, aeronautical and space applications, bulk production will be taken up by MIDHANI. DMRL has transferred the relevant technology to MIDHANI through a licensing agreement for transfer of technology.

Said an official from DMRL: “DMRL developed this forging technology by integrating various science and knowledge-based tools. The methodology adopted by DMRL is generic in nature and can be tuned to develop other similar aero engine components. The compressor discs produced using this methodology met all the requirements stipulated by the airworthiness agencies for the desired application. Accordingly, the technology was type certified and letter of technical approval was accorded.”

Explaining the importance of this technology, officials at DMRL said that like in any aero engine, the high value HPC drum assembly needs to be replaced after a specified number of operations or in the case of damage. This periodic/annual replacement is quite large and expensive. Added an official: “A HPC drum is a highly stressed sub-assembly and is also subjected to low cycle fatigue and creep at elevated temperatures. The raw materials and forgings for the HPC drum are required to be of the highest quality which can meet the specified combination of static and dynamic mechanical properties.”