Nondestructive evaluation of cracks in a paramagnetic specimen with low conductivity by penetration of magnetic fluid

This paper proposes a nondestructive testing method for detecting a crack in an Inconel® specimen. Because of the low conductivity and permeability of Inconel, cracks are difficult to detect using the electromagnetic method, until now. In our method, magnetic fluid penetrates a surface crack in the Inconel specimen, and the distribution of the magnetic field is measured using a scan-type magnetic camera. The magnetic field leakage and induced current methods were examined. With our method, cracks can be evaluated. This research can be used to detect and evaluate cracks on non-ferrous and non-metallic materials such as ceramic, composite, and synthetic resins.