Magnetic Particle Testing

Magnetic particle testing (MT) is a non-destructive testing method applied to welded joints to detect cracks, pores or other defects on the surface or near-surface areas of ferromagnetic materials. In this method, the welded material is magnetized and fine iron particles (usually magnetic powder or liquid) are sprinkled on the surface. If there is a defect in the material, the magnetic field lines deviate around this defect, which creates a magnetic flux leak on the surface. Magnetic particles adhere to this leak and create a distinct trace in the defect area.

Steps of Magnetic Particle Testing:

Magnetization: The area to be tested is magnetized with the help of a magnet or electromagnet.

Particle Application: Magnetic particles in powder or liquid form are applied to the test area.

Observation: The particles accumulate in the defective areas and make the shape of the defect visible. This observation, which can be done under UV light, makes fine surface defects more obvious.

Advantages:

It is fast and relatively low cost.

It is effective in detecting surface and near-surface defects.

It is easy to use and apply.

Limitations:

Applicable only to ferromagnetic materials (such as iron, steel, nickel).

The surface must be smooth; surface roughness may lead to erroneous results.