Magnetic Flux Leakage Inspection of Moving Steel Sheets

Abstract

In the process of making drawn and ironed cans out of a steel sheet, non-metallic inclusions such as chemical oxides in the steel sheet may cause cracks. Therefore, steel sheets are inspected before they are drawn and the magnetic flux leakage testing is usually employed for the inspection [1]. When there are non-metallic inclusions in the steel sheet, magnetic fields produced by a magnetizer leak out around such defects because of the differences in material permeability. These leakage fields are detected by flux sensitive sensors such as Hall plates or magnetodiodes [2].