PURPOSE: To make it possible to achieve the improvement of measuring accuracy and efficiency by extracting magnetic particles accumulated on a crack part on adhesive tape, and observing the magnetic particles with a microscope.
CONSTITUTION: A magnetic field is applied on the position to be investigated of a mechanical part for the surface crack, which occurs in ferrite-based steel material used as the mechanical part. Magnetic particles are applied on the part to be investigated under the applied state of the magnetic field. Then, the magnetic particles accumulated at the surface crack part is extracted on adhesive tape. The adhesive tape is put into a microscope, and the length of the magnetic particles is measured. Thus, the length of the crack can be detected. Therefore, it is not necessary to perform pretreatments such as the mirror-surface polishing of the surface of the steel material and the removal of the surface oxide film. The minute detection can be performed, and the efficient measurement can be performed by shortening the working time.
MASUYAMA FUJIMITSU
KANEKO TOKI
IMAZATO TOSHIYUKI
