Which type of discontinuities are best identified by a Straight Beam Test?

The straight beam test is primarily used to detect internal discontinuities within materials. In this testing method, ultrasonic waves are transmitted straight into the material, allowing for the detection of flaws that may be present below the surface. Such internal discontinuities might include voids, inclusions, and cracks, which can significantly affect the integrity of a material.

The method is designed to assess the quality of the material by interpreting the reflected ultrasonic waves that return to the transducer after encountering these internal flaws. By analyzing the time of flight and amplitude of the reflected signals, operators can determine the size, shape, and location of the discontinuities.

Surface discontinuities, while they can be detected using ultrasonic techniques, are more effectively identified using different methods like contact ultrasonic testing, which tends to focus on surface resolution. Volumetric discontinuities do include internal flaws but might be better characterized by techniques that provide more three-dimensional mapping of the internal structure. Geometrical discontinuities refer to deviations in the expected shape or size of a part, which wouldn't typically be the primary focus of a straight beam test.