Magnetic Particle Testing (MT) is used to detect defects in which materials?

• A. Nonferromagnetic materials
• B. Ferromagnetic materials
• C. Polymers
• D. Ceramics

Answer: (B)

Magnetic Particle Testing reveals flaws by magnetizing a part and applying magnetic particles so that any disruption in the magnetic field at a defect draws particles to that location. This works because ferromagnetic materials carry and distort magnetic fields in a way that creates flux leakage at cracks or seams, making defects visible.

Because this method depends on strong magnetization, it only works well in ferromagnetic materials like steel and cast iron. Nonferromagnetic materials such as polymers and many ceramics don’t sustain the necessary magnetic flux, so MT isn’t effective for them. In short, MT is used for ferromagnetic materials where the magnetic field can leak at defects to reveal them.