Which type of crack can be detected by magnetic particle inspection using circular or longitudinal magnetization?

The detection of cracks through magnetic particle inspection relies on the orientation and type of magnetization applied to the component. In the case of circular or longitudinal magnetization, cracks that are oriented at approximately 45 degrees to the magnetic field can be effectively detected. This is because the magnetic field will concentrate around the defect, allowing the particles to gather and reveal the presence of the crack.

When using circular magnetization, the magnetic field lines create a circular pattern around the defect, making it easier to identify angled flaws such as those at 45 degrees. This is particularly useful in identifying cracks that might not be easily visible with a straight inspection. Longitudinal magnetization, while very effective for straight cracks, does not provide the same level of sensitivity for angled defects, which further supports the advantage of detecting 45-degree cracks.

Other types of cracks, such as surface cracks, longitudinal cracks, or transverse cracks, may not be as effectively detected by this method due to their alignment with the magnetic field or the nature of the magnetic particle inspection process itself.