Feasibility study for nondestructive evaluation of magnetic properties and hardness of two-layered specimens by magnetic single-yoke probe

This work is a feasibility study for the application of a single-yoke magnetizing technique for in situ measurements of thick bulk specimens. We consider variations in the magnetic properties near the surface and inside the specimens. The magnetic properties of two-layered sheet specimens, which have different magnetic properties in each layer, are examined, and a simple summation law is consequently found concerning the relation between the magnetic parameters of the first and second layers measured by the single yoke. The relation between magnetic properties and the Vickers hardness in each layer is also inferred by regression analysis. An estimation of the hardness in each layer using a magnetic measurement by single-yoke probes is then successfully performed. These results show the possibility of nondestructive evaluation for inhomogeneous characteristics of structural materials.