Abstract
Magnetic hysteresis chacteristics have good correlation with material degradations, and magnetic flux leakage technique detects small defects in ferromagnetic steels. Both methods use a single magnetic yoke, therefore we have a potential to evaluate simultaneously material degradation and small defects using a single magnetic measurement system. In this study, we composed an electromagnetic sensor, which can measure hysteresis curves and detect leakage magnetic flux near surface of the specimen, and tried simultaneous evaluations of degradation and sub-mm sized defects. The hysteresis curves are sensitive to material degradation, while are sensitive to small defects. Though magnetic flux leakage can detect small defects, it does not show a significant change against degradation. We successfully evaluated material degradation and small defects separately with the single measurement system.
