In order to study the influence of high temperature on electromagnetic ultrasonic detection

COMSOL and JMatPro software are used to study the transducer energy conversion efficiency

acoustic attenuation and wave velocity at high temperature. The results show that the energy exchange efficiency of transducer decreases with the increase of pipeline temperature. After working at 700 ℃ for 20 min

the coil energy exchange efficiency decreases by 13. 90 %; with the increase of temperature

the acoustic attenuation is approximately exponential with temperature

and the higher the temperature

the faster the acoustic attenuation. When the pipeline temperature is675 ℃

the S-wave particle displacement amplitude decreases by 22 % compared with the normal temperature;When the temperature reaches 675 ℃

the S-wave velocity decreases by about 16 % compared with the normal temperature. Corresponding compensation algorithm for the change of amplitude and phase caused by high temperature is given

which makes the phase of signal wave packet more accurate

echo more obvious

and reduces the probability of misjudgment.