The strong need for higher efficiency, reduced CO2, NOX emissions, weight and noise reduction in aircraft engines leads to a demand of innovative materials with optimised mechanical and physical properties. The special design of new generation geared turbofan aircraft engines with their faster rotating LPT leads to higher temperatures in the turbine, casing and engine mount and thus requires parts with increased high temperature properties. High temperature strength means in most cases bad forgeability and weldability as well as combined with high toughness challenging machinability. Thus, beside of new designs the production processes have to be altered to get high quality parts.

The overall goal of this project was an improved understanding of thermomechanical processing and its effect on residual stresses and distortion as well as microstructure and mechanical properties of forgings used for improved temperature exhaust cases.

The proposed project consortium had significant experience with regard to nickel base superalloys with higher temperature capability than Inconel718 like Udimet720, Waspaloy, Allvac718Plus, RENE65 and Haynes282. Together with the know-how on residual stress simulation and measurement established in several projects since 2001 a successful realisation of this project was possible.

Beside project management according IPMA standards six further work packages had been defined. One for radial forging and one for closed die forging was used to optimise thermomechanical processes based on simulation and to produce demonstrator parts. Open die forgings were used for residual stress and microstructure investigations. Material data for finite element simulation and residual stress modelling were generated in one work package and verified together with the customer in an other. Residual stress modelling was verified by neutron diffraction measurements and other methods in the final work package.