Probe Impedance Variation
Probe impedance change is the variation in the electrical resistance properties of a material caused by defects or conductivity variations. This change affects eddy current testing and can lead to false results.
Physical-Chemical Mechanism of Action
Probe impedance change occurs when the material in the test coil is not homogeneous or has defects such as pores, damage, or contamination. These cause different conductivity and thus a different electrical resistance.
Metallurgical Relevance & Risks in Welding
In weld testing, probe impedance change can lead to false positive or negative results. This can cause safety risks in construction and mechanical engineering, as potential defects may not be detected or false rejections may occur.
Workshop Practice & Action Guidelines
To minimize probe impedance changes, it is important that the material is homogeneous and free of defects. When performing eddy current testing, the resistances should be checked regularly. If an unusual probe impedance is detected, the test should be repeated or the material checked.