Industrial radiography is a non-destructive test that consists of passing through the component to be tested with a beam of ionizing electromagnetic radiation (gamma rays or X-rays).
This radiation will be more or less absorbed by the internal discontinuities of the piece, reaching the other side of it, with a different radiation intensity, and impressing a radiographic film, which, once developed, shows the location of these discontinuities.
Ultrasonic testing is a non-destructive testing method based on the phenomenon of reflection of acoustic waves when they encounter discontinuities in their propagation. The wave will be reflected back to its source of generation if the discontinuity is in a normal position relative to the incident beam.
The purpose of these tests is to detect possible discontinuities in a part (in ferromagnetic materials) not only on the surface, but also in the vicinity of it(subsurface discontinuities).
Liquid Penetrant Testing is a type of Non Destructive Testing that detects surface imperfections in non-porous materials in both metallic and non-metallic materials.