Advanced materials for efficient jet engines

The aviation industry is increasingly looking to geared turbofan engines for more efficient flight. Innovative materials with optimised mechanical and physical properties will allow deep cuts in fuel consumptions and harmful emissions.

Geared turbofan engines may induce very high temperatures in some areas of the turbine and the engine casing and mount. The EU-funded project HITNIFO (Development of an advanced design and production process of high temperature Ni-based alloy forgings) was initiated to produce high-performance materials at low cost by improving processes, overcoming issues related to bad forgeability and weldability.

Project partners selected promising materials for the casing and mount based on nickel alloys for use in high temperatures. Firstly, they performed annealing trials to investigate changes of microstructural properties with time and temperature. The trials also enabled identifying the main impact on mechanical properties such as yield strength, elongation and stress rupture.

After designing and simulating the closed die forging process and producing dies, project partners evaluated the impact of the process on the forging microstructure and mechanical properties. Other activities included flow stress measurements at seven different temperatures and two different strain rates, and measurement of heat capacity and thermal conductivity.

Results provided the basis for finite element simulations of material residual stress. In particular, project partners performed simulations with different mesh densities to estimate the residual stress distributions in components of complex geometry. Simulations were then compared with experimental results.

HITNIFO opens the way to developing engines with higher exhaust temperatures and therefore higher efficiencies. Use of the optimised nickel-based alloys should allow a decrease in the engine weight and hence aircraft, and lead to decreased fuel consumption.