Investigation of residual stresses in new materials for the development of aircraft turbines

Investigation of residual stresses in new materials for the development of aircraft turbines

Materials and components • Stress scanning • Neutron diffraction

The Challenge

Nickel-based superalloys are particularly suited for use in turbine components, given their unique combination of high temperature strength and high fatigue strength. Their production, however requires water-quenching directly after forging, leading to much higher residual stresses than under standard air cooling. This can result in distortion of the work piece during the machining of the disc into its final shape.

The Experiment

Neutron diffraction techniques have been used to examine the residual stress distributions in a water quenched IN 718 compressor disc. With the results obtained, engineers were able to improve and validate the simulation models they use to predict residual stresses in their work pieces.

Figure 1. Residual stress distributions on the disc cross-section after water quenching, as predicted by the FE model.
Figure 2. Measured and simulated residual stress distribution through the thickness of a disc at the radius.

The Results

Optimised simulation models allow subsequent treatments – such as turning to final shape – to be fine-tuned, thus minimising unwanted distortion and deformation effects.