Differential Eddy Current Probe
A differential probe uses two oppositely connected coils to suppress homogeneous interference and focus on local flaws. This improves inspection accuracy.
Physical-Chemical Mechanism of Action
A differential probe consists of two coils that are oppositely polarized. One coil induces a magnetic field, while the other suppresses it. This minimizes the homogeneous magnetic field and increases sensitivity to local disturbances.
Metallurgical Relevance & Risks in Welding
The use of a differential probe reduces noise and improves the detection of microstructural defects, such as hot cracks or pores. However, without correct adjustment, the probe can also produce false positives or miss important defects.
Workshop Practice & Instructions
To use a differential probe effectively, ensure the coils are correctly polarized and that the probe is precisely aligned with the weld. Inaccurate adjustment can lead to missing or incorrect results. It is recommended to calibrate the system before each inspection.