In ultrasonic testing, why is echo signal amplitude important?

The importance of echo signal amplitude in ultrasonic testing lies primarily in its ability to assess the presence and size of a defect. When ultrasonic waves are transmitted into a material, they travel through the medium and are reflected back when encountering a boundary, such as a defect or the material's back wall. The amplitude of the echoed signal is directly related to several factors, including the size of the defect and its orientation.

A larger defect typically results in a stronger echo signal due to the greater surface area presenting to the sound wave, leading to a higher amplitude upon reflection. Conversely, smaller or less reflective defects produce weaker echoes. Therefore, by analyzing the amplitude of the echo signal, technicians can infer not only the presence of defects but also gain insights into their size and severity. This assessment is critical for ensuring the structural integrity and safety of materials and components in various applications.