Working principle of radiographic testing
Radiometer detection utilizes the penetration ability of X-rays and is generally used in industry to detect internal injuries or short circuits in objects that are not visible to the eyes. For example, to detect whether there is a short circuit in the internal circuit of a multi-layer substrate, X-rays can penetrate the surface of the substrate and see the internal circuit of the substrate. There is a data receiver opposite the X-ray generator, which automatically converts the received radiation into electrical signals and transmits them to the expansion board. It is then converted into specific signals in the computer, and the image is displayed on the display through specialized software, so that the internal structure of the substrate can be observed with the naked eye without the need for a multimeter to slowly test.
γ Radiation has strong penetrability, and radiographic testing is carried out using a radiometer γ The method of detecting defects based on the penetrability and straightness of radiation. γ Although radiation may not be directly visible to the naked eye like visible light, it can make photographic film sensitive and can also be received by special receivers.
When γ When a ray passes through (irradiates) a substance, the higher the density of the substance, the more the intensity of the ray weakens, that is, the less intensity the ray can pass through the substance. At this point, if a photographic film is used for reception, the sensitivity of the film will be low; If instruments are used to receive, the obtained signal will be weak. Therefore, using γ When radiation is used to irradiate the components to be inspected, if there are defects such as pores and slag inclusions inside, the material density through which the radiation passes through the path with defects is much smaller than that through the path without defects, and its intensity is weakened, that is, the intensity of transmission is greater. If a negative film is used to receive it, the sensitivity is greater, and the plane projection of the defect perpendicular to the direction of the radiation can be reflected from the negative film;
If other receivers are used, instruments can also be used to reflect the plane projection of defects perpendicular to the direction of the rays and the transmittance of the rays. In general, γ It is not easy to detect cracks in radiographic testing, or in other words, γ Radiographic testing is not sensitive to cracks. Therefore, γ Radiographic testing is most sensitive to volumetric defects such as porosity, slag inclusion, and incomplete penetration. Namely γ Radiographic testing is suitable for volumetric defect testing, but not for area defect testing.
