comparable to CMSX10.
Alloy: DMS4M
Solution Heat Treatment:
1340°C for 5 hours
1350°C for 5 hours
1355°C for 10 hours
1360°C for 15 hours, followed by air cooling
First Aging Heat Treatment:
1160°C for 6 hours, followed by air cooling
Second Aging Heat Treatment:
870°C for 20 hours, followed by air cooling
Third Aging Heat Treatment:
760°C for 30 hours, followed by air cooling
There is also DMD4, a directionally solidified alloy derived from DMS4. Developed as a columnar grain superalloy for cost-effective turbine airfoil parts. Solutionized between 1300°C and 1330°C over 30 hours.
Now the question is why aren’t we using DMS4 if we have it? I think it was because the goal was never the performance; Kaveri already had a lot of trouble back in 2010, and they were dealing with it, and on top of it, introducing an untested, new material in the engine would have complicated their already very complicated problems. Since they have chosen tried and tested CMSX4, a second-generation alloy to be used in HPT of KDE. The Kabini was using Supercast 247A; maybe that's been replaced with the superior DMD4 alloy. Kaveri was also using Superni 718A for HPC. MIDHANI has also developed the Superni-115 LPT blade blank, although it can't be confirmed if Kaveri is using it or not.
DMRL has also made low-pressure turbine blisks for STFE engines. DMRL has also worked on serpentine air cooling for SX blades.
The first KDE was delivered to GTRE in late 2024, soon followed by a second prototype, with both undergoing high-altitude testing in Russia. Where they have more or less achieved their goals. According to a report by ET, on Dec 24, 2024, after completing its high-altitude testing, the engine is ready for real-world evaluation on a flying test bed.
There is another simultaneous project going on where a redesigned afterburner is being made by BrahMos Aerospace, who won the tender in 2020 from GTRE. The AB will then be integrated with KDE and will probably be used on a dual-engine aircraft or LSP Tejas for certification and demonstration purposes.
Today, India has all the building blocks to make its own 4th-gen engine with many PSUs and private players being the first-tier suppliers for global OEMs. A lot of work is being done on composite materials to sustain temperatures as high as 2000°C. Other than GTRE, there is also the Aero Engine Research and Design Center (AERDC) of HAL's engine R&D wing, which has developed the HTFE-25 and HTSE-1200 engines, although the technology is a generation older than what is used in Kaveri. Then there is also MIDHANI, which has developed a wide range of materials since the program began, including materials like Inconel 718.
The majority of problems can be solved, and India can have its own engine with adequate manufacturing and testing infrastructure. But to be optimistic, HAL is setting up a national facility with a 50,000-ton die forge press and a 20,000-ton isothermal press. For many uses, the facility will also make titanium bulkheads for AMCA. The 20,000-ton iso press will be used to make powder metallurgy disks. Then India will need to use blisk for weight reduction of the engine. and use of composite materials in the AB.
Then there is the joint venture deal with foreign OEMs to make a 110 kN engine, which will replace GE F414-IN6 in the future, the front runners of this deal being Rolls-Royce and Safran. Both are offering everything India lacks more or less, and the deal basically includes GTRE getting know-how and know-why, a flying test bed, and other manufacturing and testing infrastructure required to make this engine. The development of this engine will take 10-15 years and will require funding of $4-6 billion USD.
