Frequency-Modulated Eddy Current Testing
Frequency-modulated eddy current testing uses varying frequencies to achieve different penetration depths in one measurement cycle. This allows depth-resolved characterization of material damage.
Physical-Chemical Mechanism of Action
Frequency-modulated eddy current testing (FMECT) uses an AC current with varying frequencies. These different frequencies affect the penetration depth of the magnetic field into the metal part. A low frequency allows a deep penetration depth, while a high frequency only reaches a shallow depth.
Metallurgical Relevance & Risks in Welding
FMECT allows detecting material damage at different depths. This is especially important for testing weld areas and other critical zones. Incorrect settings or improper execution can lead to inaccurate results, which can lead to wrong conclusions and potential risks in structures or machinery.
Workshop Practice & Action Instructions
For correct FMECT, follow these steps:
1. Set the device: Set the generator to a frequency sweep ranging from 5 kHz to 20 kHz.
2. Define the measurement cycle: Set a cycle with at least three different frequencies (e.g., 5 kHz, 10 kHz, and 20 kHz).
3. Perform the test: Run the current through the metal part and observe the changes in penetration depth of the magnetic field.
4. Evaluate: Analyze the results and compare them with reference values to identify material damage.