Which nondestructive testing method uses X rays and gamma rays to detect discontinuities?

Which nondestructive testing method uses X rays and gamma rays to detect discontinuities?

• A. Radiographic
• B. Ultrasonic
• C. Magnetic Particle
• D. Liquid Penetrant

Answer: (A)

Radiography uses high-energy photons, either X rays or gamma rays, to look inside a material. As these photons pass through, they are absorbed to different extents depending on the material’s density and thickness. Flaws such as cracks, porosity, inclusions, or lack of fusion alter how much radiation is transmitted, so when the transmitted rays are recorded on film or a digital detector, those discontinuities show up as contrasts on the image. This lets you see internal defects that aren’t visible from the outside. Other methods work very differently: Ultrasonic testing uses high-frequency sound waves that travel through the material and reflect off internal features; the pattern and timing of those echoes reveal flaws. Magnetic Particle testing magnetizes the part and uses iron particles to gather at surface or near-surface discontinuities, making them visible. Liquid Penetrant testing relies on capillary action of a dye that seeps into surface-breaking flaws and becomes visible after removing excess penetrant. Each method targets different defect types and depths, whereas radiography specifically leverages penetrating radiation to reveal internal discontinuities.

Radiography uses high-energy photons, either X rays or gamma rays, to look inside a material. As these photons pass through, they are absorbed to different extents depending on the material’s density and thickness. Flaws such as cracks, porosity, inclusions, or lack of fusion alter how much radiation is transmitted, so when the transmitted rays are recorded on film or a digital detector, those discontinuities show up as contrasts on the image. This lets you see internal defects that aren’t visible from the outside.

Other methods work very differently: Ultrasonic testing uses high-frequency sound waves that travel through the material and reflect off internal features; the pattern and timing of those echoes reveal flaws. Magnetic Particle testing magnetizes the part and uses iron particles to gather at surface or near-surface discontinuities, making them visible. Liquid Penetrant testing relies on capillary action of a dye that seeps into surface-breaking flaws and becomes visible after removing excess penetrant. Each method targets different defect types and depths, whereas radiography specifically leverages penetrating radiation to reveal internal discontinuities.