Final answer:
Demagnetization of a part after magnetic particle inspection can be achieved by slowly moving it out of an AC magnetic field of sufficient strength or by using other methods such as hammering or heating.
Step-by-step explanation:
One way to demagnetize a part after magnetic particle inspection is by slowly moving the part out of an AC magnetic field of sufficient strength. This process is called degaussing and involves gradually reducing the external magnetic field to zero, which randomizes the orientation of the magnetic domains within the material, hence removing its net magnetic field. Another common method is to subject the part to repeated hammering or heating, which disrupts the alignment of the magnetic domains, effectively demagnetizing the part.