# Enhanced Nondestructive Testing Using Pulsed Eddy Current and Electromagnetic Ultrasonic Techniques
## 1 Introduction
proposed a spiral pulsed eddy current array probe to detect and classify defects on the inner and outer walls of non-ferromagnetic pipelines [8]. [PERSON] introduced a near-field method based on pulse eddy current testing for detecting local defects in ferromagnetic metal casings [9]. [PERSON] et al. utilized frequency-selective pulsed eddy current detection (FSPECT) to determine the defect parameters of deep-shallow compound defects (DSCD) and introduced a component separation strategy [10]. However, due to the skin effect, pulsed eddy current detection is concentrated on the surface of the specimen, restricting its use to detecting surface defects only. Research into electromagnetic ultrasonic testing technology began to gain prominence in the 1970s. Notably, in 1967, [PERSON] et al. observed the generation of electromagnetic ultrasound in metals under various experimental conditions. They described the excitation process of p-waves by electromagnetic ultrasound in metals, highlighting that the intensity of the sound wave is proportional to the magnetic field intensity. They also derived a formula expressing the fraction of electromagnetic power converted into acoustic power [11]. [PERSON] subsequently proposed an analytical expression for the steady-state sound field generated by electromagnetic ultrasound, derived through calculations of magnetic vector potential. He further analyzed the impact of the coil size, the number of turns, and other parameters on the transducer's performance [11]. [PERSON] conducted research on defect detection in aluminum plates using electromagnetic acoustic transducers and achieved good detection results [12]. [PERSON] et al. proposed the use of the electromagnetic ultrasonic testing method to detect surface damages on antenna wheels, demonstrating the advantages of the electromagnetic ultrasonic method in locating, quantifying, and qualitatively analyzing surface defects on antenna wheels [13]. [PERSON] et al. employed a hybrid high-order Shear Horizontal (SH) wave electromagnetic ultrasonic transducer (EMAT) guided wave testing technique. They introduced relative energy coefficients and relative order coefficients of guided waves to accurately quantify the depth and normal displacement of hidden defects in the rail web [14]. Based on the findings of the current research, the use of electromagnetic ultrasonic testing mainly focuses on characterizing the defect depth. However, each nondestructive testing method has inherent limitations, particularly when attempting to detect objects with complex defects using a single technique [15]. The pulsed eddy current detection is affected by the skin effect, and the eddy current is only concentrated on the surface of the sample, making it challenging to detect deep defects. Electromagnetic ultrasonic detection is more accurate for deep-seated defects, while near surface defects cannot be detected due to echo overlap. In the 1970s, [PERSON] and [PERSON] proposed the combined application of pulsed eddy current detection and ultrasonic methods to inspect metal pipelines, considering the shared principles of pulsed eddy current and electromagnetic ultrasonic testing, as well as the similarities in probe structure [16]. Similarly, [PERSON] et al. proposed integrating electromagnetic ultrasound, eddy current, and magnetic flux leakage detection technologies to enhance pipeline health monitoring. Electromagnetic ultrasound is primarily used for measuring pipeline thickness, while eddy current and magnetic flux leakage testing techniques focus on the inspection of the inner surfaces of pipes [17]. [PERSON] proposed a hybrid online monitoring method combining eddy current testing and electromagnetic acoustic transducer techniques for comprehensive defect inspection in high-temperature environments [18]. [PERSON] et al. introduced a pulsed eddy current and electromagnetic ultrasonic combined nondestructive testing method for detecting both surface and internal defects [19]. [PERSON] et al.