Which testing method is designed to detect laminar-type flaws with major dimensions parallel to the rolled surface?

The correct answer is the method that utilizes a straight beam of ultrasonic waves directed perpendicular to the surface of the material. This technique is especially effective for detecting laminar-type flaws, such as delaminations or inclusions, that are oriented parallel to the rolled surface. By employing straight beam contact testing, the ultrasonic waves enter the material and can easily detect discontinuities that lie flat against the surface.

In this method, the straight beam configuration allows for clear propagation of the ultrasonic signals, which can readily interact with flat-lying flaws. This results in a strong reflection or scattering of the ultrasonic waves, indicating the presence of such flaws to the technician assessing the test results.

Other methods mentioned may not be as effective in finding laminar-type flaws oriented parallel to the surface. For example, angle beam testing is primarily used to detect flaws that are at angles to the material surface, while surface wave testing focuses on surface-breaking flaws using waves that travel along the material's surface. Through-transmission testing, on the other hand, is more suitable for evaluating volumetric internal flaws rather than specifically targeting laminar defects parallel to the surface.