Wide coil eddy current test coils are typically used to detect which condition?

Wide coil eddy current test coils are designed to assess changes in conductivity in conductive materials. This is because the wide coil can effectively generate and sense eddy currents across a larger area of the test material, which is particularly useful when examining the overall condition of the surface or subsurface layers.

When there are changes in the material's composition, such as variations in alloying elements or the presence of heat treatment effects, these will manifest as changes in conductivity. The eddy current technique is sensitive to such variations, allowing for effective detection and characterization of these conditions.

In contrast, while pitting, small inclusions, and porosity can impact the performance of a material, these conditions are generally identified using other testing methods or coil designs that are more suited for detecting specific surface defects or smaller features. Wide coils are more attuned to variations in electrical properties rather than localized defects, which is why conductivity changes are the primary condition assessed with them.