What does magnetic particle testing primarily detect?

Magnetic particle testing is a non-destructive testing method primarily used to identify surface and sub-surface flaws in ferromagnetic materials. The process involves magnetizing the material and applying ferromagnetic particles, which gather at areas of discontinuity or defects due to magnetic leakage fields. This allows for the detailed visualization of cracks, voids, inclusions, or other discontinuities that can affect the integrity of the structure.

The ability to detect both surface and sub-surface flaws makes magnetic particle testing an invaluable tool in the field of bridge inspection and maintenance, ensuring safety and reliability in structural components. By identifying these defects early, engineers can take corrective actions before issues lead to more serious failures.

The other options address factors that magnetic particle testing does not specialize in. For instance, it doesn’t provide information on the thickness of steel members or evaluate corrosion activity in concrete, nor does it detect internal structural deficiencies that are not manifesting as surface or near-surface flaws. Thus, the method is specifically tailored for finding defects that are immediately beneath the surface layer of the material.