What does a "coherency check" in Eddy Current Testing involve?

A coherency check in Eddy Current Testing focuses on the consistency of the received signals with expected patterns specific to the material being tested. This involves analyzing the nature and characteristics of the signals generated when eddy currents flow through materials. By comparing these signals against known standards, a technician can determine if the material is behaving as expected under the testing conditions. This is crucial for identifying inconsistencies that may indicate defects, variations in material properties, or issues with the testing setup.

The essence of this process is rooted in the understanding of how certain materials should respond to eddy current interactions. Consistent, predictable patterns in the signals are indicative of sound material integrity, while deviations from these patterns signal a need for further investigation. Thus, the coherency check serves as both a diagnostic and verification tool in the quality assurance process of Eddy Current Testing.