Bridging Macro- and Microscale Characterisation of Machining-Induced Surface Integrity

Machining imposes localized and heterogeneous thermomechanical loads that alter surface integrity—topography, residual stresses, and microstructure—which in turn affect fatigue, corrosion, tribology, adhesion, sealing, wettability, osseointegration, etc. Conventional macroscopic methods (e.g., hole‑drilling, XRD) yield spatially averaged data that can mask local gradients beneath and along the surface. A collaboration between Mondragon Unibertsitatea and CIC nanoGUNE compared macro‑ and microscale measurements, notably conventional XRD versus high‑resolution FIB‑DIC for residual stress mapping. Case studies show multiscale characterisation uncovers local variations and mechanisms invisible to standard techniques, underscoring the importance of combined macro–micro approaches for assessing machining‑induced surface integrity.