Characterization of acoustic emission signals in single point incremental forming (SPIF) process of AZ31B

This study characterized the acoustic emission (AE) responses of AZ31B magnesium sheets during the Single Point Incremental Forming (SPIF) process of AZ31B magnesium alloy sheets. Cup-shaped specimens with the wall angles of 10°, 20°, 30°, and 40° were fabricated, and the corresponding AE signals were analyzed. At 10°, continuous AE signals with nearly constant amplitudes were observed, corresponding to stable plastic deformation without fracture. For the wall angles of 20° and higher, three distinct stages were identified: stable plastic deformation, microcrack initiation, and macroscopic fracture. The signal RMS, energy, and frequency exhibited apparent changes during microcracking and reached extremely high values during fracture. A continuous wavelet transform analysis further revealed that the recorded AE signals consisted of both deformation- and equipment-induced components, which could be separated based on their frequency content. These findings demonstrate that AE monitoring can effectively characterize the deformation modes during the SPIF process. This study demonstrates that the integration of AE monitoring into the ISF process effectively characterizes shifting deformation modes. The established signal-processing protocol provides a foundational framework for identifying microcracking and fracture initiation, confirming the feasibility of real-time monitoring for the SPIF process.