A New Method for Internal Temperature Profile Measurement by Ultrasound

A new ultrasonic method for measuring internal temperature distribution of heated materials is presented. The principle of the method is based on temperature dependence of the velocity of the ultrasonic wave propagating through the material. An inverse analysis to determine the temperature distribution in a heated plate is developed and its validity is verified using a numerical model. Experiments are carried out in order to demonstrate the practical feasibility of the developed method. A single side of a steel plate of 30 mm thickness is heated by hot water and ultrasonic pulse-echo measurements are then performed for the steel during heating. A change in the propagation time of ultrasonic wave in the heated steel is precisely monitored and used to determine the temperature profile of the steel. The internal temperature profiles determined ultrasonically agrees well with those obtained using thermocouples installed in the steel.