Non-Destructive Testing (NDT) Practice Test

Magnetic particles used for inspection primarily originate from which material?

1. Steel shavings

2. Iron filings

3. Magnesium chips

4. Copper dust

The correct answer is: Iron filings

The correct answer is that magnetic particles used for inspection primarily originate from iron filings. This is because magnetic particle testing is specifically designed to detect surface and near-surface discontinuities in ferromagnetic materials, predominantly those that contain iron, such as carbon steel or other steel alloys. Iron filings have magnetic properties that allow them to respond strongly to magnetic fields, making them effective for highlighting defects when a magnetic field is applied. During the testing process, a ferromagnetic material is magnetized, and the iron filings are applied to the surface. Any discontinuities will disrupt the magnetic field, causing the iron filings to accumulate and form an indication at the defect location. This characteristic makes iron filings the ideal choice for magnetic particle testing, as they are capable of revealing even the smallest surface defects. The other materials listed, such as steel shavings, magnesium chips, and copper dust, are not suitable choices for magnetic particle inspections because they either do not have the necessary magnetic properties (like magnesium and copper) or are not ideal for creating the type of indication needed to effectively identify surface flaws in ferromagnetic materials. Thus, the use of iron filings is critical in ensuring effective and accurate magnetic particle testing.