Analysis of alternative current field detection signals based on complex surface defects

Alternating Current Filed Measurement (ACFM) and Alternating Current Magnetic Flux Leakage (AC-MFL) method have been widely used in engineering practice. They both use U-shaped yoke probes and are basically the same in the probe and signal processing. In actual inspection, the shape of the defect is usually complicated, and a single defect or several defects may occur at the same time. Multiple defects may appear as cross-shaped cross cracks, round-hole defects, and parallel cracks. In view of the emergence of such complex defects, the effects of cross-type cross cracks, round-hole defects, parallel cracks and ACFM and AC-MFL detection signals are studied. The experimental results show that the different crack shapes and detection signals have different characteristics, and the complex defect pairs can be comprehensively evaluated according to different defect signal characteristics. The research results are of great significance for the detection and evaluation of metal surface defects.