Abstract
This paper reports a nondestructive evaluation (NDE) method using amorphous wire MI sensors to determine the plastic deformation of steel samples. The distributions of the flux density on the surfaces of steel samples were measured. The flux density at the Lüders band was found to be clearly higher than that in non-deformed parts of the sample. The profile of contour lines for flux intensity is similar to the profile of Lüders lines. The magnetic signal from the Lüders band can be detected up to d (lift-off) = 50 mm, even for a sample covered with coating. The flux distribution for longitudinal direction of the sample was calculated, on the assumption that the magnetic poles are localized in the Lüders bands. The calculation results agree with the experimental data.
