Magnetic particle inspection (detection) principle Magnetic particle inspection is to magnetize the workpiece by applying a magnetic field (whole magnetization or local magnetization), so that the magnetic lines of force escape from the surface of the workpiece and form a leakage magnetic field on the surface and near-surface defects of the workpiece. Due to the existence of magnetic poles, magnetic particles applied to the surface of the workpiece can be adsorbed to form concentrated magnetic marks, thus showing the existence of defects.

Magnetic particle testing is widely used, mainly to detect defects on or near the surface of magnetic materials. It is mainly used to detect welds, castings or forgings, such as valves, pumps, compressor parts, flanges, nozzles and similar equipment.