Reasons for magnetic traces:

1. Localized cold work hardening, resulting in the accumulation of magnetic traces caused by changes in material permeability;

2. Magnetic powder accumulation at the interface of two different materials;

3. Segregation of carbide layer structure;

4. Magnetic traces at sudden changes in the cross-sectional dimensions of parts;

5. Magnetic traces caused by metal streamline due to excessive magnetizing current;

6. Spot like magnetic marks caused by unclean or oily surfaces on the workpiece.

Defect magnetic trace display record:

1. When using photography to record the display of defect magnetic traces, it is necessary to capture the full picture and actual size of the workpiece as much as possible. It is also possible to capture a certain characteristic part of the work, and at the same time, take a picture of the scale.

2. Paste printing is a method of using transparent adhesive tape to paste and copy defects and display magnetic traces.

3. Magnetic particle inspection - rubber casting method. Magnetic particle inspection - rubber mold embedding replication defect magnetic trace display, intuitive, cannot be erased and can be stored for a long time.

4. The shape, size, and position of the defect magnetic trace display should be recorded in the video, and the scale should also be recorded.