What type of non-destructive testing would primarily be used for surface defects?

Magnetic particle testing is particularly effective for detecting surface and near-surface defects in ferromagnetic materials. This method involves applying a magnetic field to the component and then coating it with iron particles. If there are any surface or subsurface cracks or defects, the particles will cluster around those irregularities, making them visible. This capability to pinpoint surface anomalies is what makes magnetic particle testing the primary choice for identifying surface defects.

While options like ultrasonic testing and X-ray testing are valuable for detecting internal defects, they do not specifically target surface-level issues as effectively as magnetic particle testing. Visual inspection, while useful, depends significantly on the ability of the inspector to see defects, which can be limited by the surface finish or accessibility. Therefore, magnetic particle testing stands out as the most suitable method for addressing surface defects.