Non-Destructive Testing (NDT) Practice Test

What effect does a crack in a part have during magnetic particle inspection?

1. Enhances magnetic flux

2. Creates a uniform field

3. Causes flux leakage

4. Increases particle adherence

The correct answer is: Causes flux leakage

A crack in a part during magnetic particle inspection causes flux leakage. When the magnetic field is applied to the component being inspected, the magnetic flux lines follow the path of least resistance. A crack disrupts the continuity of the material, leading to a diversion of the magnetic field lines. This disruption creates areas of weakened magnetic fields, resulting in leakage of the flux. In magnetic particle inspection, the presence of flux leakage at the site of the crack indicates a discontinuity within the material. This leakage is pivotal in detecting defects, as it allows magnetic particles to accumulate at the crack, making the defect visible under the inspection process. The accumulation of these particles helps inspectors visualize and assess the extent of the crack or discontinuity. The other options do not accurately describe the phenomenon; a crack does not enhance magnetic flux or create a uniform field, nor does it inherently increase particle adherence. Instead, a crack serves as a site for particle concentration due to the flux leakage it generates.