Online precise measurement of Si content for content graded 6.5% Si steel sheet

We have developed a technique to achieve an online precise measurement of the surface silicon content of content graded 6.5% silicon steel sheets. The technique utilizes the eddy current measurement method with minute direct magnetization for permeability control of the surface to suppress the permeability change due to variation in the silicon content. Since this technique can be achieved by the same apparatus, except for the magnitude of the magnetization, as the one which has been already developed to measure the average silicon content along thickness direction, both the surface and the average content can be measured with one instrument system by switching the amplitude of the magnetization.