No abstract

As material processing becomes continuous, the interest in applying noncontact transducer to the examination of the flaws in the materials at high temperature is increasing. In this paper, ultrasound velocities and amplitudes in aluminum, stainless steel, and steel were measured until they reached near 800°C. From the results, in the non-magnetic materials such as aluminum and stainless steel, the amplitudes and the velocities decreased monotonously as a function of temperature. But, in steel, the amplitudes changed significantly near Curie point and the velocities did not decrease monotonously. In conclusion. EMAT was successfully fabricated to endure up to 800"C by circulating water inside the transducer. In steel, shear waves must be used under 700"C and longitudinal waves could be used efficiently around Curie temperature for the application of EMAT at high temperature.