What are potential limitations of Magnetic Particle Testing (MPT)?

Magnetic Particle Testing (MPT) is a non-destructive testing method that is particularly effective for identifying surface and near-surface discontinuities in ferromagnetic materials. The correct answer highlights a significant limitation of this testing method: it is indeed limited to ferromagnetic materials such as iron, cobalt, and nickel. This is because the technique relies on the ability to induce a magnetic field within the material and use magnetic particles to reveal defects by clustering at areas of magnetic flux leakage.

Materials that are not ferromagnetic, such as aluminum, copper, or plastics, do not exhibit the necessary magnetic properties for MPT to function effectively. These materials would not respond to the magnetic field, meaning the method cannot be utilized for their inspection. Consequently, the application is restricted to a narrower scope of materials, thereby highlighting this limitation of the method.

In contrast, the other choices either present inaccurate statements regarding the capabilities of MPT or suggest capabilities that are not achievable with this method, such as the detection of subsurface defects or applicability to all materials. Additionally, MPT indeed requires trained personnel to perform inspections correctly and interpret results effectively, further underscoring the limitations of its application.