Half wave rectified AC (HWDC) is primarily used for detecting which types of defects?

Half wave rectified AC (HWDC) is particularly effective for detecting both surface and subsurface defects in ferromagnetic materials. This is primarily due to the way magnetic particle inspection (MPI) works—defects such as cracks, voids, and seams can disrupt the magnetic field, which is essential for detecting issues within materials.

When using HWDC, the magnetic field penetrates the surface layer and can reach deeper into the material, allowing for the identification of defects located beneath the surface. The method is sensitive to surface conditions, meaning that it can effectively reveal surface-breaking defects as well as those that are buried, provided they are within the effective detection depth.

In contrast, alternative methods might focus more narrowly on either surface or subsurface defects specifically, thereby lacking the dual capabilities that HWDC offers. Hence, it's recognized for its versatility in revealing a wider range of defect types, confirming that it can indeed detect both surface and subsurface defects effectively.