What property of materials is primarily tested in Eddy Current Testing?

Eddy Current Testing primarily assesses the electrical conductivity of materials. This non-destructive testing method utilizes the principle of electromagnetic induction. When an alternating current passes through a coil, it generates a changing magnetic field that induces eddy currents in the conductive material being tested. The characteristics of these eddy currents—such as their strength, phase, and frequency—are directly influenced by the material's electrical conductivity.

Changes in conductivity can indicate various conditions such as changes in material properties due to heat treatment, corrosion, or the presence of cracks. Therefore, when evaluating materials using Eddy Current Testing, the ability to measure and analyze electrical conductivity is crucial for determining material integrity and detecting defects.

The other options focus on properties that are not the primary focus of Eddy Current Testing. For instance, while thermal expansion influences how materials respond to temperature changes, it is not directly assessed by this method. Similarly, magnetic permeability is relevant mainly to magnetic materials and is not the focus of Eddy Current Testing. Density, while an important property in material science, does not relate to the electromagnetic principles governing eddy currents.