Due to its high potential for automation and the extensive range of applications, non-destructive testing (NDT) eddy current methods is an inherent part of NDT applications. These methods can be applied to any electrically conductive material. Electrical conductivity and magnetic permeability are the relevant physical material properties which influence the test and, therefore, include the information content. These parameters depend on the material‘s quality characteristics such as
• heat treatment and texture formation,
• texture differences such as case and nitriding hardness
layers, liquations etc.,
• mechanic properties such as firmness, hardness,
residual stresses etc.,
• mixing ratio of alloys.
Besides material properties, eddy current inspection is used to detect changes of specimen shapes and material defects. For example
• surface and near-surface defects,
• lift-offs and layer separations,
• corrosion layers, subsurface corrosion,
• diameter deviation of wires, rods, pipes, balls etc.,
• thickness of metallic and non-metal layers,
layer thickness of multiple conductive layers and
thickness of interlayers, pipes, sheets etc.