What does "flux leakage" refer to in MPT?

"Flux leakage" refers specifically to magnetic flux escaping from a defect during Magnetic Particle Testing (MPT). This phenomenon occurs when there is a discontinuity or a flaw in the material being tested, such as a crack or void. These defects disrupt the magnetic field, causing the magnetic lines of force to leak out of the material instead of remaining contained.

When particles are applied to the surface of the material for testing, they will cluster around areas of relayed magnetic field intensity, which indicates the presence of a defect. The escaping magnetic flux at the location of a defect is what allows for the detection of these anomalies through the magnetic particle method. Therefore, understanding flux leakage is critical for interpreting the results of MPT accurately and effectively, as it directly relates to the capability of the testing method to identify defects.