Which of the following would be considered applications of ultrasonic techniques?

• A. Determination of a material's elastic modulus
• B. All of the above
• C. Study of a material's metallurgical structure
• D. Measurement of a material's thickness

Answer: (B)

Ultrasonic techniques are versatile for nondestructive evaluation, capable of probing material properties, microstructure, and dimensions without damaging the part. You can estimate the elastic modulus by measuring how fast ultrasonic waves travel through the material and knowing (or estimating) its density; the wave speeds are tied to the material’s stiffness, so these measurements let you back out elastic constants such as the modulus. Thickness is a direct application: sending a pulse and measuring its travel time to the far surface lets you calculate how thick the part is, using the known wave speed. For metallurgical structure, ultrasound can reveal information about grain size, phase distribution, and inclusions through changes in wave velocity, attenuation, and backscatter patterns, and even map microstructure with high-frequency imaging techniques. Because each of these uses falls under ultrasonic methods, all of the listed applications are valid.