What role do wave reflections play at interfaces in ultrasonic testing?

Wave reflections at interfaces are crucial in ultrasonic testing, as they provide the primary basis for flaw detection. When an ultrasonic wave travels through a material, it encounters different media at interfaces, such as the transition between the tested material and air or a different material. At these interfaces, a portion of the wave is reflected back while the remainder is transmitted into the next medium. The reflected waves contain information about the condition of the material, including the presence of flaws, discontinuities, or changes in thickness.

These reflections allow operators to analyze the characteristics of the flaws, such as their location, size, and shape, by interpreting the time it takes for the reflected waves to return and their amplitude. The more distinct the reflection from a flaw, the easier it is for the operator to identify and evaluate the defect. Consequently, the primary results for flaw detection are obtained from these reflections, making them integral to successful ultrasonic testing.