Magnetic Testing (MT) introduces a magnetic field—using either AC or DC—into ferromagnetic materials such as nickel alloys, iron, and partially magnetic stainless steels. In aerospace applications, de-aromatized kerosene is typically used as the carrier fluid for approved wet magnetic particles. Industry standards also require the use of a Gauss meter to measure magnetic field strength, which must fall within 30–60 gauss for aerospace applications. This ensures reliable detection of local magnetic flux distortions caused by discontinuities.
MT is highly effective for detecting cracks, seams, discontinuities, and inclusions, both on the surface and near-surface of ferromagnetic materials. This makes it suitable for incoming inspections, final quality checks, and periodic maintenance. The choice of current type enhances detection capability:
- DC fields penetrate deeper, making them ideal for identifying subsurface flaws or gaps.
- AC fields concentrate on the surface, making them effective for detecting surface-breaking defects.
