On optimising ring-rolling manufacturability of C&W nickel superalloys for aero-engine turbine disc

 

A EBSD shown at x10 magnification

Ring-rolling has proven to be difficult to model, control and optimise accurately, however a team of Oxford researchers have studied multi-objective optimisation for the manufacturability of aero-engine turbine disc by integrating:

  1. geometrical constraint
  2. alloy design, and 
  3. process parameters.

Accurate computational models based on accurate experimentation which allow for knowledge-based choices of the manufacturing variables represent an important step towards an optimised ring-rolling process.  

Optimal ring-rolling formability is found by:

  1. minimising the adiabatic heating effect and stress intensity feature (geometrical constraint);
  2. developing a new C&W M647 nickel-based superalloy with an optimal ring-rolling formability at temperatures from 950 to 1050oC at strain rates between 0.1/s and 0.001/s, whilst enduring a good formability between 850 to 950oC and 1050 to 1100oC over strain rates between 10/s and 0.1/s (alloy design); and 
  3. implementing a feedback framework to control and optimise the process parameters.

Within the optimal regime, mechanical behaviour is characterised by stable and homogeneous deformation.  The findings are used to construct a processing map, on which the dominant deformation mechanisms are identified and used to develop a high-fidelity numerical tool, deducing a range of safe operating windows for an optimal crack-free result using a reduced processing time.

The results* indicate a major improvement of ring-rolling manufacturability by cutting more than 80% of processing time whilst maintaining a crack-free condition.

 

*You can read the full conference paper 'On optimising ring-rolling manufacturability of C&W nickel superalloys for aero-engine turbine disc' in Superalloys 2020.

This paper was named as the Best Interactive Presentation by the Superalloys 2020 organising committee.