Crack detection in ferromagnetic metal by low frequency magnetic flux leakage technique

A two-dimension magnetic flux density distribution of the ferromagnetic metal was simulated by using finite element analysis method. From the magnetic flux density distribution, the crack in ferromagnetic metal can be detected through the magnetic flux leakage. Experimental results showed that the magnetic flux density decreased gradually with the increasing of the width and depth of the crack under the width range of 1 to 5 mm and depth range of 0 to 6 mm, respectively.