What is eddy current testing used for in corrosion inspection?

What is eddy current testing used for in corrosion inspection?

• A. Detects surface color changes
• B. Detects subsurface cracking and thinning in conductive materials by monitoring changes in electromagnetic fields
• C. Measures thickness by ultrasound
• D. Checks paint adhesion

Answer: (B)

Eddy current testing uses electromagnetic fields to locate defects inside conductive metals. A probe induces circular currents in the metal; when there’s a flaw like a crack or thinning, these currents are disturbed, causing changes in the impedance and the magnetic field detected by the probe. By watching how the field or impedance shifts, inspectors can detect subsurface cracking and thinning, often through coatings, making it a fast, noncontact way to assess corrosion-related deterioration in aircraft structures. The other options describe different inspection methods—surface color changes aren’t within what eddy currents measure, ultrasound thickness uses sound waves, and paint adhesion checks rely on other techniques.

Eddy current testing uses electromagnetic fields to locate defects inside conductive metals. A probe induces circular currents in the metal; when there’s a flaw like a crack or thinning, these currents are disturbed, causing changes in the impedance and the magnetic field detected by the probe. By watching how the field or impedance shifts, inspectors can detect subsurface cracking and thinning, often through coatings, making it a fast, noncontact way to assess corrosion-related deterioration in aircraft structures. The other options describe different inspection methods—surface color changes aren’t within what eddy currents measure, ultrasound thickness uses sound waves, and paint adhesion checks rely on other techniques.