Non-Destructive Testing (NDT) Practice Test

What is the definition of the Direct Method of magnetization?

1. Using magnetic fields from external sources

2. Passing electrical current directly through the part

3. Cycling magnetic fields to induce magnetism

4. Coating the part with magnetic particles

The correct answer is: Passing electrical current directly through the part

The Direct Method of magnetization refers to the process of passing electrical current directly through the part being tested. This method generates a magnetic field in the object due to the flow of current, which magnetizes the part itself. As a result, if there are any surface or near-surface discontinuities, these will cause disruptions in the magnetic field, making them detectable with magnetic particle testing. This approach is particularly effective for certain applications, such as testing the integrity of welds or detecting flaws in the material. The direct application of current creates a strong and localized magnetic field, which enhances the sensitivity of the detection process for identifying defects. In contrast, the other methods mentioned refer to different techniques or aspects of magnetization. Using magnetic fields from external sources involves applying an external magnetic field to induce magnetism in the part, while cycling magnetic fields focuses on alternating the direction of the magnetic field to create different conditions for detection. Coating the part with magnetic particles, on the other hand, is a separate stage where particles are applied to visualize the magnetic field and any discontinuities but does not define how the magnetization itself occurs.