Eddy Current Testing (ET) is used to detect surface defects and near-surface discontinuities in electrically conductive materials, providing rapid inspection without the need for direct contact.
ET is an electromagnetic method where alternating current is passed through a probe that creates a magnetic field. This field induces eddy currents in the material being inspected. Changes in the material, such as cracks, corrosion, or variations in thickness, affect the current and produce measurable signal changes. The method is used internationally and is standardised under the abbreviation ET within NDT.
How the method works
A probe is moved over the surface of the material being inspected. Any discontinuities or material changes disrupt the eddy currents, which are recorded as deviations in the signal. This makes it possible to identify surface and near-surface defects quickly and precisely.
Typical applications
- Welds
- Pipes and heat exchangers
- Aerospace and industrial components
- Thin plates and profiles
The method is especially well suited for detecting cracks, corrosion, wear, and changes in thickness near the surface.
Advantages
- Fast inspection without the need for coupling media
- No cleaning required after inspection
- Highly sensitive to surface and near-surface defects
- Can be performed through thin coatings and paint