CHARACTERIZATION OF MICROSTRUCTURAL CHANGES IN COARSE FERRITIC-PEARLITIC STAINLESS STEEL THROUGH THE STATISTICAL FLUCTUATION AND FRACTAL ANALYSES OF BARKHAUSEN NOISE
Linilson Rodrigues Padovese, F. E. da Silva, Elineudo Pinho de Moura, Lucélia Lemes Gonçalves, Donald O. Thompson, Dale E. Chimenti · AIP conference proceedings · 2010
This work aims to identify the changes in the microstructure of ferritic‐pearlitic stainless steel, through the statistical fluctuation and fractal analyses of Barkhausen noise. The samples studied were obtained from pipes of steam pressure vessels, and presented coarse ferritic‐pearlitic phases before degradation. Due to temperature effects, two different microstructures were obtained from pearlite that has partially and completely transformed to spheroidite. The statistical fluctuations of the Barkhausen signals are obtained by means of Hurst and detrended‐fluctuation analyses, and the fractal analyses are carried out by applying the minimal cover technique to the signals. The curves obtained for the statistical fluctuations and fractal analyses, as functions of the time window, were processed by using pattern classification techniques such as principal‐component analysis and Karhunen‐Loève expansion. Approximately a 100% success rate has been reached for the classification of the different microstructures, and this indicates that the proposed analyses can be an effective additional tool in the study of microstructural characterization.