Why may Magnetic Particle Inspection not be suitable for all ferromagnetic materials?

Magnetic Particle Inspection (MPI) relies on the magnetic properties of ferromagnetic materials to detect surface and near-surface discontinuities. However, the effectiveness of MPI can be significantly influenced by factors such as the surface finish, thickness of the material, and the heat treatment it has undergone.

For instance, if a ferromagnetic material has a rough surface finish, it might trap magnetic particles in ways that obscure defects or make it difficult to interpret results accurately. Similarly, a thick material may not allow adequate magnetic flux penetration to reveal subsurface discontinuities. Heat treatment can alter the material's magnetic permeability, potentially diminishing the effectiveness of the magnetic field needed for the inspection process.

Understanding these limitations is crucial for selecting suitable materials for MPI and interpreting inspection results, as these factors can impact the visibility and detectability of flaws. Hence, recognizing that the properties of ferromagnetic materials influence MPI suitability provides valuable insight into the inspection process.