INCREASING THE SENSITIVITY OF ELECTROMAGNETIC-ACOUSTIC TRANSDUCERS FOR TESTING, MEASUREMENT AND DIAGNOSTICS OF FERROMAGNETIC METAL PRODUCTS VIA INCREASE IN THE VALUE OF MAGNETIC FIELD INDUCTION. OVERVIEW

The analysis of information sources on the development and usage of electromagnetic-acoustic methods and means of ultrasonic inspection, measurements and diagnostics was performed. It is shown that electromagnetic-acoustic (EMA) transducers (EMAT) with permanent magnets have significant advantages compared to piezoelectric transducers, but also have disadvantages, especially in the inspection of ferromagnetic metal products, both in normal and hot conditions, especially when using them in portable ultrasonic devices. Many experts suggest eliminating the disadvantages of EMAT with permanent magnets by using pulsed magnetization. This direction of research is promising, especially when testing hot metal, because it allows for creation of pulsed magnetic fields with a peak value of 2...3 and even 10 T, making it possible to significantly increase the sensitivity of testing, since the coefficient of conversion of electromagnetic energy into ultrasonic and vice versa depends on the induction of magnetic fields squarely. But until now, data on the widespread use of pulsed magnetization in portable EMATs has not been established. This situation is caused by a small gap between the EMAT and the metal, insufficient development of the EMAT functioning technologies, the complexity of the hardware implementation, difficulties in dealing with interferences that occur during the excitation of pulsed magnetic field, etc. Therefore, for the implementation of such a promising direction of development of sensitive EMA transducers, theoretical and practical developments are to be carried out, which is to make it possible to introduce high-tech means of inspection, measurements and diagnostics into production. References 31, figures 9.