Material properties of IS 2062 steel plates after friction stir welding has been characterized by hysteresis loop characteristics at three different frequency range; low frequency, medium frequency and high frequency range. Magnetic field was applied with sinusoidal waveform and triangular waveform over base metal and friction stir welded sample for comparative analysis. Rectangular sample of 3 mm thickness were welded using tungsten carbide tool having 15 mm shoulder diameter at 800 RPM and 150 mm/min welding speed. Micro-hardness testing and metallographic study of welded samples were also performed to study the effect of change in material properties on magnetic response of material. Grain refinement upon friction stir welding changed the microhardness of weld nugget. Depth of penetration of external magnetic field at three different frequencies ranges not only changed the shape of hysteresis loop but also resulted into wide variation in hysteresis loop characteristics such as permeability, remanence, average maximum flux density and core loss.