Which term describes the method that uses magnetic particles to reveal surface flaws?

• A. MT (Magnetic Particle Testing)
• B. UT (Ultrasonic Testing)
• C. RT (Radiographic Testing)
• D. PT (Penetrant Testing)

Answer: (A)

Magnetic Particle Testing uses a magnetic field applied to a ferromagnetic material along with fine iron particles to reveal surface and near-surface flaws. When a defect disrupts the magnetic flow, leakage fields appear at the flaw and attract the particles, producing a visible indication such as a line or indication at the crack, seam, or other discontinuity. This method is especially effective for surface-breaking flaws in ferromagnetic materials like iron, nickel, or cobalt.

The other techniques work differently: ultrasonic testing uses high-frequency sound waves to detect internal flaws, radiographic testing uses X-rays or gamma rays to image internal features, and penetrant testing uses a dye that seeps into surface openings to reveal defects. Magnetic Particle Testing stands out for highlighting surface and near-surface defects in magnetic materials.