Development and Validation of a Wireless Extrasensory BT50 Toolholder for Dynamic Cutting Monitoring of Ni-Based Alloys

Establishing an explicit correlation between dynamic machining instabilities and the terminal functional performance of difficult-to-cut materials remains challenging. Herein, a wireless sensory BT50 toolholder was deployed to in situ monitor the dynamic cutting signatures during the milling process of commercial Inconel 718 superalloy. Real-time spectral analyses captured the intensified thermo-mechanical coupling and dynamic load escalations (e.g., axial force increased from 0.56 kN to 0.65 kN) induced by progressive tool wear and anomalous grain coarsening (average grain size expanding from 45.45 μm to 56.18 μm), driven by a thermal-dominant regime at advanced wear stages and accompanied by pronounced lattice rotations and a sustained predominance of high-angle grain boundaries (HAGBs). This microstructural evolution critically governed the macroscopic corrosion degradation. The diminished grain boundary density hindered the rapid diffusion channels essential for robust passivation kinetics, whereas the highly energetic HAGB networks and reoriented crystallographic planes triggered intense localized micro-galvanic dissolution. The results formulate a comprehensive sensing-microstructure-performance closed-loop framework, offering profound mechanistic insights into the functional deterioration of critical machined components.