Magnetic particle testing (MPT) is a non-destructive testing (NDT) method that uses a magnetic field to detect surface and subsurface defects in ferromagnetic materials such as iron and steel. It is used to detect defects such as cracks, porosity, and other types of damage that can affect the integrity and safety of the material or component. The basic principle of MPT is that a magnetic field is applied to the material or component being tested. When a defect is present, it will disrupt the magnetic field, causing leakage fields to appear at the surface of the material. These leakage fields can be detected by applying a magnetic particle medium, such as a fine powder, to the surface of the material. The particles will be attracted to the leakage fields, highlighting the location of the defect. MPT can be performed in two ways: Wet method: In this method, a suspension of magnetic particles in a liquid is applied to the surface of the material. The particles will be attracted to the leakage fields and will be visible as a concentrated area. Dry method: In this method, a dry powder of magnetic particles is dusted over the surface of the material and a magnetic field is applied. The particles will be attracted to the leakage fields and will be visible as a concentrated area MPT is a versatile method that can be used to test a wide range of ferromagnetic materials and components, including castings, forgings, welds, and finished products. It is relatively simple and inexpensive, making it a popular choice for surface inspection in many industries, such as aerospace, automotive, power generation and heavy equipment manufacturing.