Internal Defect Detection in Ferromagnetic Material Equipment Based on Low-Frequency Electromagnetic Technique in 20# Steel Plate

A ferromagnetic material equipment internal defect detection system based on low-frequency (20-50 Hz) electromagnetic technique was proposed. Direct current magnetization was used to make the ferromagnetic material sample (20# steel for instance) be in a saturation magnetization state to decrease its permeability, which is beneficial for increasing the skin depth of the sample and strengthening th...