The Barkhausen effect is a response of a ferromagnetic material, that is its magnetic domains, to an imposed external alternating magnetic field. A sensor unit makes it possible to capture the so-called voltage signal of the magnetic Barkhausen noise that represents mapping of the individual characteristics of the material microstructure. The paper gives a comparison of a classical sensor unit having the magnetising and detecting sections separated and a compact sensor unit. The aim was to reduce the volume of the passive sensor unit and possibly increase the accuracy, sensibility and reliability of calibration curves. To this end two compact sensor units were developed. The first one consists of a detection coil integrated into a gap of the magnetic yoke. A comparison was made of the results obtained with a compact sensor unit having an additional ferrite core and a detection section integrated as well in the magnetic yoke. The sensor units were tested using the so-called calibration curves showing the dependence between an individual parameter searched for and a degree of cold deformation known in advance. The reference curves of calibration of cold deformation of the material plotted as functions of the calculated power of the voltage signal, the variance, the V{sub}(rms) of the voltage signal, and other estimators will be shown as a starting point for practical applications in the industrial environment. The magnetic method based on the Barkhausen noise thus permits a direct, that is non-destructive, determination of the condition of a Fe360-B structural steel by describing the steel hardness achieved with different degrees of cold deformation.
展开▼
