What can the results of eddy current tests indicate about a material?

The results of eddy current tests primarily provide information about the electrical conductivity of materials. Eddy current testing operates on the principle of electromagnetic induction, where an alternating current in a coil generates a magnetic field that induces eddy currents in the conductive material being tested. The characteristics of these eddy currents, such as their amplitude and phase shift, vary with changes in the material's electrical conductivity.

When a material has higher electrical conductivity, the eddy currents can penetrate deeper and produce a different response in the testing equipment compared to a material with lower conductivity. This relationship allows inspectors to assess changes or variations in the material that could indicate flaws, surface conditions, or other factors related to conductivity. Therefore, this method is particularly effective for detecting defects like cracks or changes in thickness in conductive materials.

While thermal properties, mechanical strength, and chemical composition are also important characteristics of materials, they are not directly assessed through eddy current testing. The technique quantitatively correlates more closely with electrical properties rather than the other attributes listed. Thus, the answer regarding electrical conductivity is the most accurate choice in the context of eddy current testing results.