Non-Destructive Testing (NDT) Practice Test

When inspecting aluminum for cracks, which NDT methods can be used to confirm findings?

1. Radiographic and Magnetic

2. Visual and Penetrant

3. Ultrasonic and Visual

4. Magnetic and Penetrant

The correct answer is: Visual and Penetrant

When inspecting aluminum for cracks, using visual and penetrant methods is effective. Visual inspection allows for the immediate identification of surface defects such as cracks, inclusions, or other irregularities that may be present on the surface of the metal. This method relies heavily on the inspector’s ability to recognize these defects visually. Penetrant testing complements visual inspection by utilizing a liquid penetrant that seeps into surface defects. After a dwell time, the excess penetrant is removed, and a developer is applied that draws the penetrant out of any cracks or voids. This results in a visible indication of the defect, which aids in confirming findings that were initially suggested by visual inspection. Other methods mentioned, like magnetic testing, are not applicable to aluminum since it is non-magnetic. Radiographic testing may also not be the best choice for surface crack detection in aluminum, as it is generally more suited for volumetric defects rather than surface cracks. Ultrasonic testing can also be used but is more complex and typically used for internal defects rather than confirming surface findings. Thus, visual and penetrant testing provides a suitable and effective combination to confirm surface cracks in aluminum.