What does "A-Scan" depict in ultrasonic testing?

In ultrasonic testing, "A-Scan" refers specifically to the representation of reflected ultrasonic pulses over time. It provides a graphical output that plots amplitude on the vertical axis and time on the horizontal axis. This display allows the operator to visualize the time-of-flight of sound waves as they bounce back from internal features or flaws within a test object, such as cracks or inclusions.

When an ultrasonic pulse is sent into a material, it travels until it encounters an interface, such as a flaw or the back wall of the material, and gets reflected back to the transducer. The display effectively shows how strong each reflection is (amplitude) corresponding to when it occurred (time). This information is critical in determining the depth and severity of any indications observed.

Understanding this graphical representation helps operators interpret the severity and location of flaws, thereby enabling effective assessment and quality control in various materials. The other options, while they involve aspects of ultrasonic testing or related concepts, do not accurately describe the A-Scan display’s focus on amplitude in relation to time.