In a 6-inch thick aluminum plate, how will a discontinuity parallel to the surface at 3 inches be best detected?

For detecting a discontinuity that is parallel to the surface of a 6-inch thick aluminum plate and located at a depth of 3 inches, a straight beam test is the most suitable method. This technique involves sending ultrasonic waves directly into the material from a transducer that is aligned perpendicular to the surface.

In this scenario, since the discontinuity is parallel to the surface and positioned at a specific depth, a straight beam allows for direct reflection of the ultrasonic waves from the discontinuity back to the transducer. The straight path taken by the waves makes it easier to locate and characterize the discontinuity, as the waves will reflect off the flaw and return, creating a distinct signal on the screen of the ultrasonic testing equipment.

Other methods, such as angle beam tests, are typically used to detect flaws that may not be directly below the transducer; they rely on the change in the angle of incidence to improve detection of discontinuities that are oriented at specific angles to the beam direction. This makes angle beam testing less effective for a discontinuity parallel to the surface. Through transmission tests involve sending an ultrasonic wave through the entire material, which may not adequately target a specific flaw located at a half-depth. Immersion tests usually require the part to be submerged