Non-destructive testing on stainless steel plate by rotational magnetic flux sensor

In order to estimate non-destructively a defect shape on the reverse side of a thick stainless steel plate, we improved a rotational magnetic flux sensor with a three-axis search coil. By using specimens with a defect, we investigated the relationship between the defect shape and output signals of the three-axis search coil. From results of our experiments, it can clearly distinguish several types of the defect shape existing on the reverse side of sensing surface. In this paper, we present the construction of the rotational magnetic flux sensor with the three-axis search coil, results of numerical analysis and experimental results