BIFROST Biaxial Fatigue Resistance @ Oscillating Stress and Temperature on forged and AM Inco718

Purpose and goal:

Compare material behaviour and damage mechanism between wrought and additive manufactured (AM) Inco718 under thermomechanical and bi-axial loading conditions.

The main driver for this work is the desire to increase the operating temperature of gas engine turbines to enhance their efficiency. This leads to reduced fuel consumption and CO2 emissions. Another focus is to expand the use of AM, which offers design freedom and less material waste. The proposal seeks to develop reliable methods to assess the material behaviour of both wrought and AM Inco718 under service-like conditions.

Expected results and effects:

Better understanding of the differences in fatigue behaviour between wrought and AM produced Inco718. The GKN strategic need can be summarized in two research questions, with the first expected to be addressed by this project:

- How do the material properties and damage mechanisms differ between wrought and AM Inco718 when subjected to thermomechanical and bi-axial loading?

- How can observations from laboratory conditions be utilized to describe and predict the behaviour of materials under the complex conditions found in an aircraft engine? Approach and implementation:

The project is planned to support the first 4-years of a 5-year PhD project at Chalmers University of Technology, focusing on experimental investigations.

The first step is to study the thermomechanical behaviour under uniaxial loading, literature data will be used to compare and verify the method and results. The method will then be extended to biaxial thermomechanical loading, where limited published results exist. The verified method will be used to study AM produced materials. Considerable effort will be devoted to microstructural characterisation.