Magnetic Particle Testing (MPT) is a widely used inspection method for identifying surface and near-surface discontinuities in ferromagnetic materials.

During the testing process, a magnetic field is applied to the component. When a defect interrupts the magnetic field, it creates a local flux leakage. Magnetic particles are then applied to the inspection area, where they gather around the leakage points and form visible indications of the defect.

This makes MPT particularly useful for locating fine cracks and other discontinuities that may not be easily visible during a normal visual inspection.