Thickness measurement of corroded steel plates by an electromagnetic method using a step exciting current

摘要

Applicability of an electromagnetic method using a step exciting current to measurement of the thickness of corroded steel plates was investigated. This method employs the electromagnetic response of steel picked up by a sensing coil at the opposite side of a steel plate to the exciting coil with a step exciting current. Measurement area determined by experiments is about 150mm in diameter and the effect of roughness and slits of steel surfaces on the measurement are minimal. The relationship between the value of the waveform of the electromagnetic response of steel, delay time, and the thickness of steel was formularized by an electromagnetic model of the measurement. Finally, applicability of the technique to corroded steel plates was determined by an experiment using such plates obtained from a wrecked ship.