Introduction of two commonly used radiographic inspection techniques

Date：2021-08-31 13:26:38 Views：2276

X-ray testing technology is one of the five traditional non-destructive testing methods, which has been widely used in industry. It is applicable to metal detection and non-metal detection. Radiation detection can be carried out for possible defects in metal, such as holes, pinholes, inclusions, looseness, cracks, segregation, incomplete penetration and insufficient fusion. Applications include special equipment, aerospace, ships, weapons, hydraulic equipment and bridge steel structures.

Radiographic inspection technology is a common and important inspection technology to detect internal defects of materials. Gamma rays and X-rays are two common types of rays. The basic principle is as follows:

X-ray: when high-speed electrons hit some solid surfaces (targets), they will produce special rays (electromagnetic wave frequency 3) × 1016-20hz, wavelength 10-6mm);

γ Radiation: radioisotopes (such as cobalt 60) can produce very short wavelength electromagnetic waves, i.e. gamma rays, reaching the speed of light.

Radiation has strong penetration. When light shines from one side of the material, it will penetrate the material and make the film on the other side sensitive to show the detected defects. It can also be converted into visible light and the detected defects can be displayed by TV camera. X-ray computed tomography analysis can determine the location and spatial size of defects.

Radiation test is mainly used to check shrinkage cavity, air hole, non-metallic slag inclusion, etc. of castings and discontinuity of welds. It is characterized by intuitive defect detection, long-term storage of negative electrode, wide range of applicable materials, low cost, and the operation ability and experience level of operators are lower than the requirements of ultrasonic testing.

The comparison of the two radiographic detection technologies is as follows:

Y radiation detection technology - the instrument has the advantages of large volume, inconvenient carrying and high penetration. For thick materials (steel parts 120mm), no attenuation, adjustable radiation source intensity. It is harmful to human body and requires power supply;

Radiation detection technology - the instrument has the advantages of small volume, convenient carrying and strong penetration. It is used for thick wall materials (steel parts with a maximum of 300mm), attenuation, non adjustable radiation source intensity, harmful to human body and no power supply.