The magnetic properties of ferromagnetic materials are very sensitive to the mechanical treatment and condition of the material [1]. Therefore magnetic methods for non destructive evaluation of the mechanical properties of steels have received increasing attention in recent years. Techniques ranging from magnetic Barkhausen measurements [2,3,4], magnetoacoustic emission [5,6], residual magnetization [7], field rotation [8], hysteresis [9] and flux leakage [10,11] have all been developed with varying degrees of success.