One way a part may be demagnetized after magnetic particle inspection is by

One way a part may be demagnetized after magnetic particle inspection is by

• A. slowly moving the part out of an AC magnetic field or sufficient strength
• B. quickly removing the part from an AC magnetic field
• C. placing the part in a strong DC field
• D. heating the part

Answer: (A)

Demagnetization after magnetic particle inspection works by removing the magnetizing field in a controlled way so the material’s magnetic domains return to a random orientation and leave little residual magnetism. Slowly moving the part out of the AC magnetic field (or letting the field strength gradually drop) accomplishes this because the field decreases gradually enough for the domains to lose their aligned orientation without “locking in” a residual magnetization. If you remove the part quickly, the field collapses too abruptly and some magnetization can remain, causing residual magnetism. Placing the part in a strong DC field would magnetize it further rather than demagnetize it. Heating might reduce magnetism in theory, but it isn’t the standard or reliable method used after MPI because it can alter the part’s properties or distort features.

Demagnetization after magnetic particle inspection works by removing the magnetizing field in a controlled way so the material’s magnetic domains return to a random orientation and leave little residual magnetism. Slowly moving the part out of the AC magnetic field (or letting the field strength gradually drop) accomplishes this because the field decreases gradually enough for the domains to lose their aligned orientation without “locking in” a residual magnetization.

If you remove the part quickly, the field collapses too abruptly and some magnetization can remain, causing residual magnetism. Placing the part in a strong DC field would magnetize it further rather than demagnetize it. Heating might reduce magnetism in theory, but it isn’t the standard or reliable method used after MPI because it can alter the part’s properties or distort features.