Which materials can be inspected using magnetic particle inspection?

Magnetic particle inspection is a non-destructive testing method primarily used to detect surface and near-surface discontinuities in ferromagnetic materials. The technique relies on the application of a magnetic field to the material, which can be achieved through either the creation of an external magnetic field or by inducing a magnetic field within the material itself. When iron alloys, such as steels and certain cast irons, are exposed to this magnetic field, any surface flaws or inconsistencies will disrupt the magnetic flux, leading to the formation of visible indications as magnetic particles accumulate at the defect sites.

Iron alloys are particularly suitable for this type of inspection due to their ferromagnetic properties, allowing for effective and accurate detection of faults. In contrast, materials like plastics, copper alloys, and non-ferrous metals do not exhibit the necessary magnetic characteristics for magnetic particle inspection to be effective. As a result, the correct answer reflects the inherent properties of iron alloys that align with the principles of magnetic particle inspection.