Remanent magnetization of steel plates after being magnetized by moving magnets

Abstract

Inconsistent initial magnetization of ferromagnetic specimens may result in low signal-to-noise ratio and poor consistency in detecting defects and stress anomalies of magnetic methods. One of the solutions to the problem is to magnetize specimen in advance and make it magnetized uniformly. Via theoretical analysis, finite element simulation and experiment verification, the distribution of remanent magnetization and remanent flux density of steel plates after being magnetized by moving single and dual magnets is studied. The results show that the remanent magnetization of the steel plate becomes uniform and in the same tangential direction of the magnet moving. The remanent magnetization inside the steel plate is layered, and the magnetization between different layers may be opposite. However, the magnetization of each layer is uniform, and the tangential remanent magnetization is large, while the normal remanent magnetization is small. The longer the length of the steel plate specimen, the longer the flat area of the magnetic flux density near the surface after magnetization, and the value of the flat area is closer to zero. The research results provide important guidance for the magnetization method and the defect detection scheme design.