Exploration of corrosion defect detection of tank bottom plate based on electromagnetic acoustic emission

This study investigates the feasibility of detecting corrosion-induced defects in tank bottom plates using electromagnetic acoustic emission (EMAE) technology based on high-intensity pulsed current excitation. Experiments employed intact and electrochemically corroded Q235 steel specimens simulating the bottom environment of storage tanks. Key findings demonstrate that EMAE with pulsed current excitation successfully induced distinct acoustic emission signals in corroded specimens, exhibiting significantly higher intensity compared to intact specimens. Crucially, corroded specimens displayed a pronounced Kaiser effect, characterized by rapid attenuation of signal intensity and energy within the characteristic frequency band of 46.875-62.5 kHz upon repeated loading at identical current levels, a phenomenon absent in intact specimens. Time-frequency analysis confirmed that this characteristic frequency band is uniquely present and exhibits Kaiser effect attenuation exclusively in signals from corroded specimens. Parametric analysis further revealed distinguishing waveform features associated with corrosion signals. These results validate that electromagnetic acoustic emission (EMAE) with pulsed current excitation can effectively generate and detect acoustic emissions linked to active corrosion defects. The identified Kaiser effect behavior and the specific 46.875–62.5 kHz frequency band serve as diagnostic indicators for corrosion detection. This study lays the groundwork for applying this EMAE methodology to corrosion detection in tank bottom plates.