What kind of defects can MPI specifically identify on a material's surface?

The identification of surface and near-surface defects is the key strength of Magnetic Particle Inspection (MPI). This non-destructive testing technique is specifically designed to detect discontinuities such as cracks, laps, seams, and porosity that occur in the outer layers of a material. MPI works by magnetizing the component and applying ferromagnetic particles, which gather at defects, making them visible under appropriate lighting conditions.

Since MPI focuses predominantly on surface and near-surface areas, it is well-suited for detecting flaws that could affect the integrity of the material, especially in critical applications such as aerospace, automotive, and structural components. This capability is crucial because many failures in materials initiate from surface defects that propagate inward over time, leading to serious safety concerns.

In contrast, the other options either refer to phenomena that MPI cannot assess directly or focus on different aspects of material integrity. For instance, temperature discrepancies involve thermal analysis, while underlying structural failures pertain to issues located deeper within the material that MPI does not typically address. Similarly, wear and tear might be observed, but MPI is not aimed at identifying them unless they manifest as observable defects on the surface.