It is well known that the integrated Barkhausen noise (IBN) depends on the grain size, d, while the inflexion point of the IBN versus exiting field curve is proportional to the coercivity, B_c, which is sensitive to the internal stresses of the sample. These (semi)empirical correlation’s have been proved for microcrystalline samples and are used e.g. for the control at the site of the stress sate of railway rails. However, it is not known that whether these relationships are also valid or not in a nanocrystalline state as well. This can be very important in the understanding of the formation of the surface corrugation, caused by the surface loading and can be related to the formation of a nanocrystalline (or Bilby) layer. In our measurements – for modelling the formation of nanocrystalline layer on the magnetic properties – ball milling of railway rail materials was carried out. It was shown that the correlation between the point of inflexion of IBN and B_c (determined by the vibrating sample magnetometer) is still valid in the nanocrystalline region. Similarly there is a definite correlation between the maximum of IBN values and d, although it is different form that observed in a microcrystalline state. Measurements on railway rails at the site were also carried out and will be discussed.