Derivation of empirical models for transverse wave velocity in high-temperature materials

Ultrasonic wave velocities are critical for Non-Destructive Testing and are significantly affected by temperature. Transverse wave is an important waveform for online monitoring because it cannot be disturbed by liquid media. Although theoretical formulas exist to calculate transverse wave velocity in materials, they can only calculate transverse wave speeds at specific temperatures because material parameters, such as Young's modulus and Poisson's ratio, vary with temperature. To improve the measuring accuracy of transverse wave velocity at any temperature, a high-temperature test system is set up, and a waveguide measurement method is designed. The transverse wave velocities in four commonly used high-temperature materials for pressure vessel systems are researched. These include three pressure-bearing materials (304 stainless steel, 316 L stainless steel, and Q235A steel) and one non-pressure-bearing material (45# steel, used for components such as agitator shafts). The maximum measurement error of the waveguide method is 2.11%, which is significantly smaller than that obtained using the electromagnetic ultrasonic method and the high-temperature transducer method. Furthermore, empirical models of transverse wave velocities in four materials were established, enabling the precise calculation of velocities at any temperature. These models overcome the limitations of classical theoretical formulations that rely on Young's modulus and Poisson’s ratio values, thereby improving the accuracy of ultrasonic testing in high temperatures.