Remote Field Eddy Current Test in Carbon Steel Tubes

The magnetic domains of silicon steel sheet, which was not magnetized and was loaded on different intensity or direction, were observed with the Bitter method. The effect of stresses on magnetic domains and the magnetic signals ΔB was then analyzed. The results show that there mainly exist 180° gladiate domains for the silicon steel sheet with low load or no load, with their walls being small in the same crystalline grain. Then, with the load enhancing, the domain walls length and space are changed and the mazy domains appear. The number of the mazy domains and the magnetic signals of ΔB increase with the load increasing.