Magnetic NDE with magnetic yoke-probe for degradation and mechanical properties of steel

Abstract

Magnetic NDE techniques for an estimation of distribution of degradation in tensile-tested structural steel and for an evaluation of mechanical parameter alike hardness in low carbon steel have been developed. In order to scan magnetic properties of steel promptly, a magnetic yoke-probe having primary and secondary coils wounded around the yoke was adopted. To simplify the detection procedure, the same principle as a transformer and the impedance measurement using the secondary coil were employed. The voltage induced at and the impedance of the secondary coil decrease with the increase of applied tensile stress. As for the spatial distribution of the measured parameters, the induced voltage and the impedance at the center part of specimen which was subjected to a large stress decrease, and the area where the induced voltage and the impedance decrease becomes wider with increasing applied tensile stress. The induced voltage and the impedance decrease with increasing hardness in low carbon steel. © RILEM 2013.