Comparative analysis of three types of EMAT detection performance in high-temperature aluminum alloy laser electromagnetic ultrasound

Currently there are three forms of probe configurations for laser electromagnetic ultrasonic inspection of high-temperature aluminum alloys. They are Meander line coil (MLC) electromagnetic ultrasonic transducer (EMAT), in-plane EMAT, and out-of-plane EMAT. However, there are challenges, such as poor signal-to-noise ratio of echo signal and unclear application occasions of the three types of Laser-EMAT in the process of high-temperature detection. Therefore, a finite element model of multi-physical field coupling analysis of high-temperature aluminum alloy laser electromagnetic ultrasonic detection process was established. Subsequently, the influence of temperature on the reception efficiency of the three types of EMAT was analyzed, and the capability of the three types of EMAT for the detection of surface defects was explored. By conducting surface wave detection studies of the three types of EMAT for Laser-EMAT of aluminum alloy plates at high temperatures, the applications of the three types of EMAT were determined. The results established that the out-of-plane EMAT has the best reception performance, and the received surface wave signal has the highest amplitude, the best resolution. Then the out-of-plane EMAT was designed to optimize parameters such as the permanent magnet height and width, coil width, coil-wire diameter, and coil pitch. Finally, high-temperature aluminum alloy crack detection was carried out, and the experiments established that the out-of-plane EMAT can receive a defect wave of 86 mV at 500 ℃.