Non-destructive procedure to determine residual stresses and white layers in hole making operations

Holes are one of the most critical features of aero-engine components subjected to fatigue loads. Thus, it is essential to ensure a good surface integrity during hole making operations. This work proposes a non-destructive procedure based on X-ray diffraction measurements to determine residual stresses and white layers in holes. Drilling tests were done in Inconel 718 using new and worn tools for different cutting conditions. The results showed that residual stresses can be determined non-destructively with ±150 MPa error. Importantly, Full Width at Half Maximum values showed an unequivocal agreement with the presence of white layer and plastic deformation.