What are the surface and near-surface limits of magnetic particle inspection, and it is best to have a source?

Magnetic particle inspection is a nondestructive testing method to detect surface or near-surface defects of ferromagnetic materials. Its basic principle is to use magnetic field to generate leakage magnetic field at defects on or near the surface of ferromagnetic materials, and to absorb magnetic powder to form magnetic marks, thus displaying or amplifying defects. This method is widely used to detect surface or near-surface defects of various steel materials and workpieces.

There is no uniform standard for the detection limit of the surface and near surface of magnetic particle flaw detection, because it depends on many factors, such as the nature of the detected material, the type, size, direction and depth of defects, the sensitivity of detection equipment and the skills of operators. Therefore, it is difficult to give a specific numerical range as the detection limit of the surface and near surface of magnetic particle inspection.

However, for different applications and testing requirements, corresponding flaw detection standards are usually formulated. For example, conventional flaw detection standards require that the length of surface defects of steel parts to be detected should be greater than or equal to 0.5 mm and the depth should be greater than or equal to 0. 1 mm. However, the high-sensitivity flaw detection standard requires that the length of surface defects of steel parts is greater than or equal to 0.3mm and the depth is greater than or equal to 0.05 mm.

Please note that these are only some examples and cannot be used as a general standard for surface and near-surface detection limits of magnetic particle inspection. In practical application, appropriate flaw detection standards and detection schemes should be formulated according to specific conditions.

As for the specific sources, the relevant standards and specifications of magnetic particle inspection are usually formulated and published by national standardization organizations or industry associations. For example, International Organization for Standardization (ISO), American Society for Testing and Materials (ASTM) and Chinese National Standard (GB) may all have relevant standards and specifications for magnetic particle inspection. Therefore, it is suggested to consult relevant international or domestic standards to obtain more specific and accurate information.