In magnetic particle testing, an electromagnetic field is commonly used due to its ability to produce a stronger magnetic field and its versatility in application. This type of magnetic field can be generated quickly and can be adjusted to suit the requirements of the specific test and the material being inspected.
Electromagnetic fields are particularly effective for magnetic particle inspection because they can penetrate the surface of the material and detect surface and near-surface discontinuities effectively. This is essential in non-destructive testing, where the goal is to identify flaws without damaging the tested component.
While static magnetic fields and residual magnetic fields can also be utilized, they do not offer the same level of control and strength as electromagnetic fields, making them less common in practice. Dynamic magnetic fields might also be used in specific applications, but this is not standard for most magnetic particle inspections. Thus, the electromagnetic field remains the most widely used and preferred method in the field of magnetic particle testing.