RI-AM Research Seminars: Plastic deformations induced on the workpiece surface when machining Ni-based superalloys: From Macro to Nano studies

For particular aerospace components made of Ni-based superalloys machining is regarded as a key enabling technology to deliver surfaces at required geometrical accuracies and surface quality. An aspect of particular importance, but often neglected, is the surface integrity resulting from machining operations; this includes the metallurgical and mechanical property alterations of the machined (sub)surface with inherent influence of service life of the components.

The presentation gives an overview of surface quality requirements and possible anomalies that might appear during machining with defined cutting edges (e.g. drilling, milling, grinding) of Ni-based superalloys. Particular importance is given on how the process parameters/machining strategies should be conducted so that metallurgical/surface damages are minimised while resultant mechanical properties (e.g. residual stresses, micro-hardness) are favorable for enhancing the lifing of the components. Here, it will be presented not only standard surface examination techniques (e.g. SEM, XRD) but also state-of-the-art material evaluation/testing methods (e.g. TEM, EELS, EBSD, Raman spectroscopy, SEM micro-pillar testing), that are very seldom employed by manufacturing community, to enable in-depth understanding of the governing phenomena for the workpiece surface integrity formation. Particular attention is given on plastic deformations occurring at different scales under the machined surface and link them with the physics of the cutting process.