The comprehensive online detection of defects and inclusions in cold rolled strip with a thickness < 0.5 mm is commercially realised by magnetic flux leakage technique (MFL technique) using a magnetisation system in combination with magnetic field sensors (1). In the described study, the detectability of the small size inclusions in the steel sheets with a thickness more than 0.5 mm up to 1 mm has been tested. The GMR (giant magneto resistive) sensor has been used as a magnetic field sensor. An important point of the design optimisation was to increase the air gap between the inspected steel sheet and the sensor (sensor lift off). The results achieved on the test specimen with artificial defects are presented in this contribution.
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